Unfortunately I can't find Ricelia/Ooo's orchestral arrangement of the Elite 4 theme on youtube. And by the way, I've never actually played Gen 3, so it's not nostalgia.
That being said, I liked the music for pretty much every Gen, so I find it hard to vote. Gen 1 and 2 had catchy and memorable tunes that were made better by Gen 4. DPt had really nice jazzy town themes offered by Sato, and another of the composers, Ichinose, seemed like he had a sudden Impressionism epiphany shown in tracks like Mt. Coronet. And dat bass. Gen 5 was really solid all around too, with some of the best battle themes to date. I was slightly disappointed with the Gym Leader arranges, but I realize Masuda wanted them to sound as close to the original tracks as possible.