Simple, name the video game(s) or series you think that have the best soundtrack. Personally, I think that Midnight Club Dub Edition Remix had the best one.
Score or sound track? They are different things.
If it's sound track, it's GTA: Vice City (although I'm willing to wiggle on this and give to SA, I think VC vs SA soundtrack is an age thing).
I couldn't name you a good score because I almost always inevitably turn it down after the first week and promptly forget it. Honestly, GTA V/O has a really good score, varied with lots of ground covered, when I can be bothered to listen to it. But I'm not fixed on that answer, because as per previous reasons I don't pay attention.