#1 Phantasy Star Online 2
Truly a standout soundtrack, not only is the quality of the tracks amazing but it has technology behind it too, remixing the tunes on the fly to better suit the situation at hand, from calm tunes as you explore to storming themes as you engage hordes in multiparty areas to the everpresent danger of the taiko beat telling you everything's gone to hell.
some of my favourite tracks:
Big Vader Theme
It's hard to imagine anything as epic as a guy with a sword taking on a battleship sized mech with hundreds of cannons, turrets, lasers and missile launchers, but this track evokes that feeling so well.
Dark Force Arm's Theme
This one embodies the game as a whole I feel, mixing the memorability of the old with new style. It has some familiar tunes in there for fans of the original PSO while putting it more in pace with the large scale multiparty combat taking place.
Dark Ragne Phase 1-5
This track shows the evolution of the music pretty well, the boss has 4 legs and as you destroy each one it gets angrier and tougher and the music moves it up a notch too.
#2 Sonic & Sega Allstars Racing Transformed
I couldnt forgive myself if I failed to mention a game that has some of the best sega tracks ever, all remixed by Richard Jacques, I mean come on, a sega fans dream right there.
Skies of Arcadia
After Burner
Golden Axe
#3 Atelier Meruru
Gust games pretty much universally have fantastic OSTs, of the Arland Trilogy I definitely felt this was the best one thanks to a bit more input from Achiwa and Nakagawa.
Astarte
I really enjoy this track, they just totally let rip with guitar and piano for a track that screams it's time to go crazy and use everything you've got.
Astral Blader
Another brilliant battle theme, not quite as mental as Astarte, this one turns it back a notch and goes for something grander because you're going to be in for a longer fight for this one.
Honorable Mentions
Double Dragon Neon gets a mention just for that ending theme
Armored Core V
Rainbow Moon good thing the battle music is decent, you'll be hearing a lot of it
Gundam Extreme Vs it was actually released about this time last year but I dont think it got much mention, or ever will, since most tracks are from the anime, the awesome original tracks for the game are a bit overlooked, but they are great.