I seriously considered Sapphire/Ruby/Emerald, but I decided on DPP because I spent so many long hours on Route 12. The music from it just holds a special place in my heart.
I voted for B2W2. Dragonspiral Tower, Reversal Mountain, Strange House... they all had really good songs. That being said, I will also always love the music from RBY. It's so nostalgic for me. I especially love Lavender Town's music.