>>19956400good question. thinking about it, aside from bw2, the johto remakes'd prolly be up there, too. lots of great colour, two regions, battle frontier, walking pokemon, pokeathlon, plus a cute little gadget. that level curve thing was really bad, though, and drags it down a rather large amount.
last spot? i'm not totally sure.
platinum was also pretty awesome, fixing a lot of dp's problems. i don't think there's anything "wrong" with platinum bar the battles being rather slow; the modern battle frontier was put into place here, and it was pretty great. nice graphics, the distortion world was "whoah" and seeing the cutscene beforehand was badass. fairly tough gym leaders. the region felt rather "cold" overall, though, and not just in the literal "snow" sense - though i don't like snow, i'm canadian and see that shit for at least six months of the year. it just felt... odd. likewise, didn't like too many new pokemon.
emerald was my first [as i got into vidya rather late due to not having money for them and also having an illogical fear of them for some reason, my first console was the xbox even though the 360 was out already], so i'm probably biased in that regard, but those colours were really vibrant, hoenn had a lot of memorable locations, and i liked hoenn's pokes quite a bit - also, secret bases are ballin'. the battle frontier was also pretty good, even if i didn't understand advanced breeding [not that i'd really do it either way - gen 3 breeding? ick] - eastern hoenn kinda sucks, though, and the evil team baddies have a retarded motive.
so, yeah, third spot'd prolly be between those two.