For me, the stand has got to be my favourite, simply because of size. Its got enough scope to always be interesting to me.
In terms of characters, I can never remember their names, but I really enjoyed the vampire in Salem's Lot. It was a new look on vampires, and seemed like a perfect mix of bpth the archetype of vampires as primal, hungry things and as cunning schemers.
The mosr conceptually interesting in my opinion is a slightly more obscure book called "desperation" about a group of people trapped in the desert with some kind of unknown pagan spirit.