Hmm...
I don't mind Kanto, but I'd love a DS remake on a bigger and better scale, the GBC and GBA ones aren't enough. I love all the starters, especially the Charmander family!
Johto is OK, but I've had the least experience with it. Seems a bit small really, and I'm not keen on the set of Pokemon. Some I like, but the starters are meh, I always choose Totodile as it's the only one I love, and I don't really like Feraligatr, but I have to evolve it because it'll be too weak :(
Hoenn is boring as a region to me :( While I love the starters and all their evolutions, I think I've played it so many times I'm bored of it :p Also, the Surf from Petalburg to Slateport is literally the worst segment of a Pokemon game ever, it's far too long and soooo boring!
Sinnoh is a great region, probably my fave. I can never choose a starter, cause I love them all so much, especially Chimchar! There's a good balance between water, caves and other features so you don't get bored easily. And there's plenty of Pokemon I love!
Can't comment on Unova really, I'll wait for B/W to be out here. But I love what I've seen of the Pokemon in hacks I've played, even though they can't use their new moves and they're usually without the cry they'll have in B/W.