Peragus was good for what it was. I'm on Telos now, and I haven't seen much of the game yet.
In KOTOR:1, Taris was the only world of size or substance. Manaan's city was boring, but I dug the underwater aspect. Tatooine is just Tatooine. It doesn't take any ingenuity to design what we've seen a million times. Dantooine was nice, but again, nothing spectacular.
Korriban didn't have incredible visuals either, but was the best world for roleplay purposes.