Like sibling rivals, social media darlings Facebook (NASDAQ:FB) and Twitter (NYSE:TWTR) can't escape comparison, for better or worse.

Both companies helped insert social media into our mainstream consciousness, and their respective IPOs were among the most hyped in all of tech in the last five years. At the same time, although Facebook encountered its own post-IPO swoon, their experiences trading in public markets tell a story of largely divergent paths.

FB Chart

FB data by YCharts

However, with both their business models still evolving, Facebook and Twitter also offer investors a number of fascinating growth opportunities. So in an effort to determine which social media stock holds the greater long-term opportunity, we recently polled a number of our technology contributors to get their views of whether Facebook or Twitter is the better buy today.

Andrew Tonner (Facebook): To be clear, I'm very enamored with Twitter and all its recent changes. If Dorsey & Co. can lead a product renaissance at Twitter, the reward will likely be substantial for those prescient (or lucky) enough to have purchased in advance. That's a sizable "if" though, and largely why Facebook makes more sense from a risk-reward perspective in my eyes.

To me, Facebook enjoys more readily identifiable levers it can pull in order to realize its still-lofty valuation. For starters, Facebook's user base, as defined by monthly active users (MAUs), is currently an astounding five times that of Twitter's, and Facebook is aggressively innovating on the product front to create new avenues through which it can increasingly monetize its 1.5 billion MAUs.

Two especially useful examples are Facebook's Instant Articles publishing platform and its recently launched revamped storefronts. Both initiatives are explicit attempts on Facebook's part to keep users engaged in the platform, which directly correlates to the number of advertisements the social media giant can serve to its users. Beyond Facebook proper, meaningful potential growth drivers, including WhatsApp, Instagram, and Oculus, could each evolve into their own platform-sized businesses in years to come, which certainly doesn't diminish Facebook's investment appeal.

That being said, although Twitter has yet to scale to the point of consistent profitability, Facebook stock remains more expensive than Twitter's by some measures, as evidenced by their respetive 18x and 11x price-to-sales ratios.

However, despite the sticker shock that comes with Facebook shares, I still see it as the higher probability candidate for realizing its valuation, even when accounting for recent tailwinds at Twitter.

Source: Twitter

Daniel B. Kline (Twitter): Betting on Twitter being a better investment over the long-term potential of Facebook is the stock market equivalent of an NFL team signing Tim Tebow and making him its franchise quarterback. You know he's a former first round pick who managed to win despite not having a conventional skillset, but there's plenty today suggesting he's just plain bad and his success was an aberration.

The same is true for Twitter. If you buy it now, you're buying based on future potential, unlockable potential, and the idea that "coach" (CEO) Jack Dorsey can somehow put it all together. It's a long shot, but it could be a cheap bet, with Twitter trading at less than a third the price of its more successful rival. It's betting on a long shot, but it's a long shot that has had past success, which, with the right leadership, could be possible again.

It was not all that long ago that Facebook itself was seen as a failed prospect. The company stumbled out of the gate after its IPO mostly due to monetization struggles. That's one of the major problems facing Twitter, and it's one which history has shown can be solved. If Dorsey can figure out how to add users, increase time on-site, and solve the monetization problem, then Twitter could quickly post some major gains. It may not catch up to Facebook, but it offers more opportunity for investors, though it's also a much bigger risk.

Source: Facebook

Tim Brugger (Facebook): At first glance, Twitter seemingly offers more upside than Facebook thanks to its recently sagging stock price. Add to that Facebook's push to $100 a share, and some investors may lean in Twitter's direction. That said, what differentiates Facebook from Twitter is its multiple, clearly defined avenues for years of continued growth.

The digital advertising market in general, and mobile spots in particular, is sky-rocketing. This year global digital ad spending is expected to reach $170.5 billion, $64.25 billion of which will be of the mobile variety. The shift to mobile fits Facebook like a glove, given that over 1.3 billion of its MAUs access the site on the go. Coupled with the staggering growth of mobile advertising spend, Facebook's future looks awfully good.

But the growth of digital ads tells only part of the Facebook growth story. Taking the monetization wraps off its wildly popular Instagram, with its 400 million plus MAUs will almost certainly add to Facebook's top and bottom lines. This year alone, Instagram is expected to generate about $700 million in revenue, and it's just getting started.

And let's not forget the billion WhatsApp MAUs who will, eventually, begin to add to Facebook's sales coffers, as will its budding virtual reality (VR) hardware unit, Oculus, slated for mass distribution in early 2016.

Sure, Twitter's recent layoffs were favorably received by investors, as demonstrated by its 5% price pop in early trading. But for long-term investors, there's no need to live with the uncertainty of Twitter when Facebook's roadmap for the future is there for all to see.