Amazon may be the king of e-commerce, but some smaller online retailers are giving the company a run for its money.

Shares of Stitch Fix, Wayfair, and Etsy are all handily outpacing behemoth Amazon this year, up 101, 91 and 50 percent, respectively, versus Amazon's relatively paltry gain of roughly 12 percent.

Tuesday was Stitch Fix's best day ever. The stock gained as much as 40 percent after the company beat earnings and revenue estimates and topped analyst expectations for active clients.

While some might view the company's strong quarter and the stock's positive reaction as reason to pick up shares, S&P Global's Erin Gibbs and Newton Advisors' Mark Newton argue that among these e-commerce retailers, Etsy is actually the best one to own.

"I like Etsy quite a bit. … [It] has just broken out a couple of weeks ago and has really been consolidating of late," Newton said Tuesday on CNBC's "Trading Nation."

Newton also believes the stock has a "much better technical chart than stocks like Stitch Fix." And despite Etsy's roughly 28 percent gain in the last month, Newton said investors "can buy at current levels" since the stock appears to be heading "to the upper 70s" and maybe even "as high as $80." It closed Tuesday's session at $71.15.

On the other hand, Newton is staying away from Stitch Fix, saying the stock has "gotten well ahead of itself" and needs to pull back. He says he would be a buyer around $31.50 — about 7 percent lower than where the stock was trading Tuesday.

Because Stitch Fix, Wayfair and Etsy are small-cap stocks — with market capitalizations of $3.4 billion, $15.7 billion and $8.5 billion, respectively — they can be more susceptible to volatility. So while all three have soared this year, S&P Global's Erin Gibbs says part of the gain in Stitch Fix and Wayfair can simply be attributed to a rebound from last quarter's steep losses.

But she does like Etsy due to the company's growth trajectory and upward momentum.

"It's earnings are just as stable as its stock price. It's the only one that's really growing. The others are just rebounding from massive decimation of profit expectations and I would be very hesitant to get in," she said. "Etsy is the one that really is growing steadily and actually has expanding profits."