Zankyou no Terror has a gorgeous one! I've been listening to it a lot lately. I will second Samurai Champloo, and the Evangelion rebuild films have a nice one too!
If we're talking full OST's, then my choices are probably out there. I love Black Lagoon's full OST, Death Note's OST, Baccano's OST, Air Gear's OST, FMA: Brotherhood OST's, and Welcome to the NHK's OST. There's more just because I like music, but for the most part, those are my go-to's to listen to for enjoyment.
Kenji Kawai. He did some pretty awesome work on Ghost in the Shell and Gundam 00. Another artist of note is Yasuhara Takanashi, he did really good on Log Horizon.http://youtu.be/pdg7Q9f4tvo
Hmm the ending song of Clannad. The Dango song. Gives me feels.
I will second Samurai Champloo, and the Evangelion rebuild films have a nice one too!