In Phase 1 of the MCU, the villains ranged from bad (Abomination) to okay (Red Skull) to great (Loki).
Phase 2, most of villains where Luthor (2016)/Enchantress level bad (Ronan, Malekith) to meh bad (notmyMandarin, Strucker) to okay yet forgettable (Yellowjacket, Pierce), to good. Phase 2 had the worst villains imo.
Phase 3 so far, has okay villains with potential (Zemo, Ayesha, Dormammu), to a very good villain
And one bad villain, Kaecillus. But a lot of villains have a lot of potential for these upcoming movies.