Baron Zemo's fantastic in the context of Civil War, but otherwise forgettable IMO.
Loki's fantastic too, but I give it less props because we all know it and I overlook it when I probably shouldn't, perhaps because I don't really see him as a Villain at all or even main antagonist of any film but the blandest, safest films in the series, Avengers Assemble, and Thor.
Winter Soldier's dead on, excellent design and gimmick- but a Villain? No, victim.
Don't really have anything to say about the others.
