Sinnoh. I like the idea of what it is based off of, and some of the cities are great (Snowpoint cities being one of the few I like), but the problem is the layout. I think Pastoria should be where Canalave is, Jubilife city should be where Veilstone is, Veilstone and Hearthome should be made into one and then placed where Floaroma is, Floaroma should be put in where the general vicinity of Pastoria and made into a port, and finally there should be another port on the west side to make up for Pastoria taking over Canalave.
Whew. That was a mouthful.
I's also say 50% of the crappy instrumental music needs to be tossed. And definetely different tilesets for D/P/Pt.
And did I mention Lickilicky? That was definetely one of the biggest fails of Pokemon. Rhypherior and Yanmega were alright, but not Lickilicky.