The southern ashlands. Probably because I've never played Morrowind, so it's completely new to me. It's oddly beautiful, and I can't quite work out why. Also, Apocrypha is beastly.
Tel Mithryn. Place just looks cool and the people who reside there are awesome in general. The badass and bastard () wizard Neloth and his apprentice are always practicing magic or conversing on matters arcane. Outside you get a clear-water view of Red Mountain and just a little west hear the Silt Strider cry out