LR was the best OST of the FFXIII games IMO. It was a nice mix of different genres and had some memorable tracks. It's everything I expect to hear from an FF game.
FFXIII-2 went for a more experimental style with all those vocals, rap and what not. Personally, it didn't take for me as music to listen to, but it wasn't awful in the actual game. Plus my fave vocal theme of the FFXIII series, Caius' Theme, came from this game ^^
FFXIII sound great at arms length, but I didn't feel it has much over-all variety. One criticism I had was that some of the Latin songs were way over the top, to the point where I didn't really like listening to in-game. Not to mention, some songs were just too long and didn't really fit as battle music.
All 3 soundtracks are great. I give a slight edge to XIII-2's soundtrack for being the most creative in my opinion. I have all 3 on my MP3 player. --- My pembroke welsh corgi: http://kupokupo83.imgur.com/all/
Wow, I'm the opposite of most it seems. I think it got progressively better (I loved a lot of Lightning Returns') but I thought FFXIII was a big big drop in quality compared to Uematsu's work with the previous FFs.
But Lightning Returns' music was really great and creative. I think it was just listening to the field music in The Dead Dunes when I realized how impressed I was. Some of the battle music for the random encounters at the end of the game are A+ as well.
XIII was pretty good, albeit a bit samey at times. XIII-2 was fantastic, with some absolutely fantastic variety and themes. LR was a fitting end to the series and close to XIII-2 in quality. All three also had absolutely stunning production values, so odds are they're not going to age. --- This is a signature.