It’s been three and a half years since Google introduced the very operating system we write about everyday – Android – and every major (and many minor) United States carrier has phones running it. Some more than others, of course, but who has the best lineup? I take a gander at offerings from Verizon, AT&T, T-Mobile, Sprint, US Cellular, MetroPCS and more and at the end I’ll let you know who I think has the best Android lineup. Let’s get started!

AT&T

It’s no secret that AT&T got off to a slow start when it comes to Android. Blame it on Apple, blame it on the alcohol, blame it on whatever – they’ve caught up and have done so marvelously. They now offer a number of high-end phones from the likes of Samsung with their soon-to-be-released Infuse 4G, HTC with the Inspire 4G, and Motorola with the ATRIX 4G. And it’s not just because they have a “4G” tag on them – they are damn good phones.

The ATRIX 4G, for instance, was the first phone on the market with NVIDIA’s dual-core Tegra 2 processor inside. It had 1GB of RAM, a qHD display, fingerprint scanner and with the help of an accessory or two, it could transform into a netbook. Choice is always a big factor, though, and they’ve proved that they can manage a diverse lineup offering different products at different price points. The HTC Aria can be had for one cent on a two-year contract and it is by no means a bad device for the crowd it’s aimed at.

The only thing holding me back from giving AT&T all the love I have is the fact that they still don’t allow you to sideload applications on Android phones. It may not be as huge of a deal to others as it is to me, but trying to lock users into one ecosystem because you don’t want them to scrape a knee is irritating. AT&T also doesn’t offer a lot compared to other carriers, but quality and quantity are two different things. For the most part, they offer quality.

Sprint

Back in 2009, Sprint followed T-Mobile in embracing Android early on. They came to town with the HTC Hero, the first Sense device that had everyone wanting it for the software alone. (Including yours truly. I went as far as flashing a Hero ROM on my original G1. Yes, it was painful but it was well worth it.) Times have changed, of course, and Sprint has proven they can keep up with those times. They were the first to market with a 4G Android phone in the HTC EVO 4G. It surpassed their previous high-seller – the Samsung Instinct.

And more than it was popular, it was just good. In fact, I don’t think any Android device to launch on Sprint since the EVO has topped its sales. They had heavy hitters like Samsung’s Epic 4G – a Galaxy S with a QWERTY keyboard – and a smaller keyboard-enabled cousin in the HTC EVO Shift 4G. Even though they weren’t as successful, they were every bit as good. Sprint also offers a number of cheapies in the Sanyo Zio, the Samsung Transform and the LG Optimus S. The former-most isn’t that good of a phone but the latter-most will blow you away with its speed and stability when you consider how cheap it is compared to high-end beasts.

More than just affordability, though, Sprint’s looking to separate themselves with unique products. The Kyocera Echo is the first of its kind – the phone can fold out into a dual-screen tablet-esque device and allow you to multi-task like you never have on a phone. We’re still having trouble getting behind this one, though, as third party software that takes advantage of the phone’s dual screen capbailities has yet to take off.

The upcoming Nexus S 4G (it’ll be here May 8th) won’t be a bad device, either. In fact, it may just end up being their new best device once it’s available. Sprint doesn’t have many options but the ones they do have are fantastic and they stand by them. They’re usually quick about software updates and the software preinstalled doesn’t get in the way as much as they do on other carriers’ devices. Sprint is held in high regards with me.

Verizon

Verizon’s army of Androids began with an iconic device – the Motorola DROID. Many credit Verizon and Motorola with single-handedly slingshotting the platform into relevance and making it a household name and a mainstream entity. Since then, they have released many devices under the DROID name and most of them have lived up (at least in quality) to the standard that the original set. No, we’re not counting the DROID Eris, folks.

Many of those DROIDs have been phased out for new renditions, though, which include the Motorola DROID PRO, Motorola DROID 2, Motorola DROID X, and the HTC DROID Incredible 2. Samsung was also blessed with their first DROID-branded phone recently – the Samsung DROID Charge. (Though that has been delayed and still has not been released as of the time of this writing.)

All of these devices may not be the best fit for you or me, but there’s no doubting their impressive performance in specs. The DROID line has become an exclusive stable of phones that you can expect to be powerhouses every time Verizon announces one.

There are others, though, such as the Samsung Fascinate, the Samsung Continuum, and the HTC Thunderbolt. While we’re not particular fans of the second one, the other two aren’t too shabby themselves. (And it makes us wonder why they weren’t given the DROID tag.) The HTC Thunderbolt is one of particular interest considering it was Verizon’s first 4G phone, but others will soon eclipse it.

And for business types, they really believe in securing your hardware with options like the DROID Pro. For those who do field work, the Casio g’zOne Commando provides durability and great functionality. You can’t go wrong with one of Verizon’s devices no matter who you are. Big Red is definitely near the top of the curve.

T-Mobile

T-Mobile was the first carrier in the world gutsy enough to adopt Android. It all began on October 22nd, 2008 with the now-legendary T-Mobile G1. As much as we loved the device, though, Android quickly outgrew its clothes. It’s been officially discontinued but not without some devices worthy of replacing it. For starters, T-Mobile has continued the “G” line with two smash mouth devices that everyone currently enjoys – the T-Mobile G2 and the G2x.

The first is a stock Android device with a great QWERTY keyboard and an optical trackpad that pays homage to the original. The dual-core spinoff – the G2x – has NVIDIA’s dual core Tegra 2 processor and is the first stock Android device to carry that load. T-Mobile’s going to keep the “G” brand going with nothing but stock Android devices, it seems, so you’ll always have a carrier to go to if you need one of those. They are also FOR hacking and encourage folks like Cyanogen and other developers to do exciting things with the hardware. They really get a lot of bonus points for that.

They have a slew of devices from HTC, Samsung and Motorola and are currently the exclusive carrier of the Nexus S. (That’s going to change in four days, though.) The MyTouch line keeps rolling with devices tailoring to those who need a great looking device with powerful features, but still easy enough to learn to use. And while selections from Motorola aren’t all that great, they deliver a big punch for the asking price. You can’t go wrong with T-Mobile. (Unless AT&T buys them. Ouch.)

US Cellular

US Cellular has increasingly made a name for itself over the past year releasing devices such as the HTC Desire and the Samsung Mesmerize, a Galaxy S phone. Unfortunately, the number of less capable phones far exceeds that of their high-end devices with offerings such as the Samsung Gem, the Samsung Acclaim, the LG Apex and the LG Optimus U. US Cellular, like many of the carriers following it, are wallet-conscious and consumers flock to them for that very reason. If you want an affordable Android with an affordable rate plan, they’re top dog.

MetroPCS

MetroPCS had a disappointing lineup early on, but their selection has been heavily bolstered by two top-notch Androids. The LG Optimus M is a great option like all Optimus One phones are, but for the same price you’ll get the 4G LTE-enabled Samsung Galaxy Indulge. They aren’t calling it a Galaxy S phone, but it might as well be one with its 1GHz Hummingbird processor and a very nice slide-out QWERTY keyboard. And at only $300, you’d be a fool to pass this up if you enjoy MetroPCS’ service. That’s where we’ll draw the line, though, because simply cannot endorse the Huawei Ascend.

Boost Mobile

Boost’s Android lineup is less exciting. Their options include the Motorola i1 – a smallish Android operating on a soon-to-be dead network – and the Samsung Galaxy Prevail. The latter is a decent option and very affordable at $180, but even then there isn’t a whole lot to get me excited here. If you want a good selection of phones, Boost isn’t the best place to look.

Cricket

Cricket has three smartphones – two of them are Android and both of those are bad. I’m talking about the Huawei Ascend and the Sanyo Zio. Sure, a smartphone for less than $150 seems great on paper (and to your wallet), but don’t expect to save the planet with these.

So Who Has The Best Overall Selection?

This is such a difficult choice to make. There are a lot of compelling options through MetroPCS. I can tell you now that the bottom two won’t make the cut. At the end of the day, it depends on what you as a consumer want or need. Factors other than how good a phone is play into one’s decision such as its cost or the cost and quality of the carrier’s service. I’ve based my decision on variety, depth, support and quality, though, and with that I name the victor – T-Mobile.

Perhaps it’s the rooter in me, but there’s something about Magenta’s open arms toward device customization that I am thrilled with. Some carriers fight tooth and nail to lock their devices down and the first thing they’ll check before they service your phone is to see if it’s modded or rooted in any way. T-Mobile has openly admitted that they’re fans of developers like Cyanogen and that they always look forward to seeing what cool things folks do with their devices.

Their selection is top notch, too. They have a very nice stock Android dual core offering in the T-Mobile G2x – this won me over for those two combinations alone. While their high-end offering may not run as deep as Verizon’s, AT&T’s or Sprint’s, what they have come to the table with is nothing short of impressive.

The Sidekick has never looked so good, the MyTouch line offers a unique take on HTC Sense and HTC’s design practices and the “G” series will always make the development community flock to them. Don’t forget about the HTC Sensation, one of the OEM’s flagship devices that’ll have a 4.3 inch display and a dual core processor. Their willingness to carry Nexus devices is also nothing to take for granted. Don’t let the looming merger deter you, either – it could very well end up being denied and that won’t happen for a while anyway.

That’s not to say T-Mobile will remain at the top of the list in the coming months, though. This industry moves extremely fast and I wouldn’t be surprised to see Sprint, AT&T, Verizon, US Cellular or any of the others top this list after they bring their next generation of devices. For Sprint, the picture will change a ton once the dual-core HTC EVO 3D and the Nexus S come out. And we hear they’re getting some decent dual core devices pretty soon. Likewise, Verizon has a lot of nice phones too and their selection alone already made it difficult for me to put them ahead of T-Mobile.

What do you guys think? Who has the best selection of phones from smallest to biggest and cheapest to bank breakers? Vote in the poll below and I know you want to put your own $.02 in so the comment section is open for debate. Go!