Now playing: Watch this: Firefox's new mobile OS in action on the Geeksphone Peak

BARCELONA, Spain--Although mobile phones will always have a central role at Mobile World Congress, this year the red-hot buzz went to software, tablets, wearable tech, and other geeky-cool oddities.

With heavy hitter HTC announcing its flagship HTC One days before MWC, and Samsung saving its Galaxy S4 announcement for March 14, it was the sensible, midrange Android phones that made up the bulk of the announcements.

However, it was the outlier operating systems that really stole the show.

Firefox, Ubuntu, Tizen: The other, other OSes

The mobile, browser-based Firefox OS appeared on several smartphones, like the Geeksphone Peak (our pick of the bunch), the Alcatel One Touch Fire, and the ZTE Open.

LG and Huawei Firefox phones also made an appearance under glass, and Firefox has locked down carrier partners to bring its -- frankly, rather green -- OS to emerging markets for cheap.

Ubuntu Touch OS impressed on an LG Nexus 4 and Google Nexus 7 tablet, and Samsung's Tizen OS came out for an early look.

The usual suspects

MWC 2013 saw a mini trend of large-screen devices (you might call them phablets), like the LG Optimus G Pro, the ZTE Grand Memo, and the Alcatel One Touch Scribe Easy.

Sarah Tew/CNET

There was also a larger trend of wallet-friendly options like the Samsung Galaxy Grand, the Alcatel One Touch Snap, and the Acer Liquid E1 and Liquid Z2.

On the Windows Phone side, Nokia took top honors with the Nokia Lumia 720, a nice midrange Windows Phone 8 device with many of the features you also see on the higher-end Lumia 920.

A step below, the Lumia 520 is notable for its low price, but strong feature set -- 139 euros (a little under $200) unlocked. U.S. customers should pay attention, since a variant will also arrive on T-Mobile as the 521.

Sarah Tew/CNET

Weirder fare

We also enjoyed unique devices like the rugged Cat B15 Android Jelly Bean smartphone and the dual-screen NEC Medias W N-05E.

In nonsmartphone land, we liked the SpareOne Plus, an emergency cell phone that runs on a AA battery. The Nokia 105 also made headlines for its ridiculously low retail price of 15 euros.

As with CES last month, MWC 2013 gave the smaller brands a chance to prove their worth.