Yeah, which is yours? to me, it's BW2, because of the remixes, especially the Neo Team Plasma gutar solo part, and with Ghetsis' theme, you can feel his insanity listening to it. The BW themes were also good to me, but BW2 made it better. But DPP is decent, the others... meh.
Heartgold Soulsilver had fantastic music and had my favorite Pokemon song, the National Park theme. Platinum was also really good, and had really great piano music as well. I would have to say 4th gen, and Soulsilver was probably my favorite, what a fantastic remake.
3DS FC: 1134-8061-2200; SV 3273; IGN: Dano; List: http://tinyurl.com/meg2s5l Beartic, Piloswine, and Snorunt - My Friend Safari is Ice because I'm so cool.
Gen 1 has pure nostalgia going for it, but gen 2, and more specifically the gen 2 remakes, probably have the best soundtracks in the series. Gen 3 has a good E4 theme and Regi music though and the PWT in gen 5 has some good remasters of past themes. Gen 4 has the Giratina theme in Platinum.