5,1,2,3,4
I didn't like the DP trainer battle theme when I first heard it in 2007 and I still don't now. Mainly the "herp derp let's repeat the same five notes over and over again for 12 measures" - seriously wtf was that.
RSE's was decent, but forgettable. I was about to put GSC over RBY but after listening to them both again I'd have to put RBY ever so slightly above GSC.
I still stand by BW having the best in the series. They really pulled out all the stops for that and just about all of the music in that game.
But yeah, if we're talking all music then I'd put DP's way higher, since the rest of its music lineup was very strong. Fight/Survival Area, Routes 209, 210, 216, 225, 228, all the legendary battle themes, the bicycle theme, Game Corner, Sunyshore City (day), and the (yeah Pt) Battle Frontier boss theme are some of my favorites in the series.