Whenever I think of Favorite Soundtracks or music I immediately think of Sonic The Hedgehog CD. Supposedly there are 2 OST's for CD, so my favorite is the Japanese version. Stardust Speedway is my favorite track in any Sonic Game, Sonic Team may be terrible at making games, but they always deliver quality music. Sonic The Hedgehog 2006 backs that claim up.
At the moment i'm playing through Tales of Zestria for the first time, even though I hate the game, the OST on the other hand is something that stays in my mind. Specifically the temple themes which are by far the best songs in the game, and the theme of Zaviida. Other than that most of the OST is sadly not onto par.
NieR is definitely another game I think of, which also has one of my favorite battle themes of all time. Kaine Salvation and Emil Karma being my favorite OST's in the game. This game picked me up after experiencing the tragedy that is Final Fantasy 13. It's a great OST.
Before getting into Sonic, I grew up with Eiyu Densetsu and basically all of the Falcom Games, like Ys and the Kiseki series. Zero no Kiseki Evolution is probably my favorite of the Falcom OST's. It's great, especially the rearrangement of Get Over The Barrier, which I suggest listening to, it's the main theme of the game in battle version basically. I also love Sora no Kiseki SC's OST. Unfortunately I just bought Evolution and they messed up a lot of my favorite songs including "Looking Up at the Sky"
My first Playstation 2 game was Xenosaga, which one of my favorite PS3 games, my favorite being Tales of Symphonia or Shadow of The Colossus. I'm a huge fan of the Xeno Series and their music, it's always almost flawless. Xenoblade Chronicles brought in the sacred hand of Yoko Shimomura for the main theme, and the rest of the OST is godlike. I ean Xenoblade Chronicles is almost at the top list of my favorite games, and ost's ever. The Story and music fit so perfectly together. Especially Engage The Enemy with the cutscene at the bottom of Valak Mountain. Unfinished Battle during the only time it plays,Refugee Camp, this OST is flawless,
I had finally got my hands on Xenoblade Chronicles X for a month, and I don't see what the fuss is all about with the OST. I personally love most of the tracks, seriously Sawano did better than I thought he was going to do, and i'm happy about that. If you haven,t just listen to these tracks: NO EX01, MONOX, Mira, Oblivia(Day), Sylvalum(Night), Noctilum(Day and Night), The Way, Uncontrollable, ZField. It's a great OST to listen to while playing through such an expansive game, as good as Xenoblade Chronicles OST? No, but it's great for the tone and feeling of X.
One thing Final Fantasy still does right is it's music. As much as I despise the Final Fantasy 13 Series I do like a couple of the songs like Sabers Edge and Eclipse Aggressive. Some of my old FF OST's being 8 and 6.
Some good mentions are the Kingdom Hearts 2 and Dream Drop Distance OST, Beat The Angel from Tales of Symphonia, Life or Death from Tales of Xillia.