The majority of modern video games are mixed for 5.1 or 7.1 surround in addition to stereo, but the actual quality of the surround sound is only as good as the game's audio team can make it. Some games definitely make for better testing than others.
Here are the first five games I use to test a new surround-sound headset, as of January 2017.
A surround-sound gaming headset can make for a more immersive singleplayer experience, but it can also give an edge in competitive play. Blizzard's sound design for Overwatch is remarkably consistent, particularly the way that footsteps echo around the battlefield. The game makes it easy to locate and differentiate the pitter-pat of an enemy Tracer or the heavy clomps of a hostile D.Va. A good set of headphones should have no trouble making it clear where everything is happening at any given moment.
Battlefield games have long had impressive sound design, and the folks at DICE have got this stuff down to a science. While Battlefield 1's explosive audio hellscape isn't always that useful in a practical sense for testing positional isolation, it's good for seeing just how much a headset can handle. It's also useful for testing out how well a headset mixes voice chat with game audio. Planes drone overhead, mortars explode off to your right, bullets snap off the rocks next to you, and soldiers scream in the trenches ahead. With all that going on, it's important to also keep track of what everyone on your team is saying. Usually some variation of "Oh shit, there's a tank on Butter!"
Grand Theft Auto V
GTA V is a couple of years old but it still has some of the best audio engineering of any game I own. Not only is there an absurd amount of aural information in any given scene, it's all mixed well, which makes it possible to pick out individual sounds over the din of traffic or the noise of combat. First-person mode makes the surround sound stage even more immersive and complex. If I want to see how much sonic information a pair of headphones can handle, I hop on a motorcycle, crank up the radio and get into a high-speed chase.
Part of the reason I use Destiny to test a new headset is because I'm so familiar with it. I know every sound by heart, from the charged snap of a Queenbreaker's Bow to the springy thwop of a Nightstalker's quiver shot. The positional audio in Destiny PvP can actually get a little bit funky in my experience, and there are times when players will sound closer or farther away than I was expecting. But Destiny's overall sound design is fantastic, I've played so much that it makes for a solid frame of reference.
I don't think of Doom as having a particularly complex sound-stage, mainly because its battles tend to take place within enclosed arenas and the sound effects and music are so purposefully overstimulating. But it does make for a good stress test for the bottom end of a pair of headphones, as well as for any possible distortion as demon screams, chaingun fire and dank heavy metal all fight for prominence. Plus, I'll always take the opportunity to play more Doom.
There you have 'em — the first five games I play when testing out a new pair of headphones. Anytime I set up a new audio system, it's fun to see how it can handle the best-sounding games I've got. That's just me, though — what are your go-tos when trying out new speakers or headphones?