I'd like to see...
Captain America: The Civil War - Baron Zemo / Masters of Evil
Doctor Strange- Baron Mordo (Dormammu as a background villain)
Guardians of the Galaxy- Korvac (Thanos in the background)
Thor: Ragnarok - Loki, Enchantress, Surtur
Black Panther- Klaw
Avengers: Infinity War Part 1- Kang (Thanos in the Background)
Ms. Marvel- Moonstone (Thanos in the background)
The Inhumans- Maelstrom (Thanos in the background)
Avengers: Infinity War Part 2- Thanos w/ the full Gauntlet.
Captain America: Civil War, honestly should be Iron Man and the U.S. government. Though I do think Crossbones will take him out. Maybe in this universe Winter Soldier takes his bullet. Guess we'll have to wait and see.
Doctor Strange has to have Baron Mordo with Dormammu puppeting. Totally.
Guardians of the Galaxy 2 is a toughy. Korvac and The Badoons would be cool, but I'm kind of leaning towards an evil Adam Warlock (The Magus) and the Universal Church of Truth. He is seen and has been confirmed by Gunn that his cocoon was broken and he was released from The Collector's collection.
Thor: Ragnarok... It'll definitely be Surtur. As well as The Midgard Serpent. With Loki and Enchantress attempting to scheme. (I'd love to see The Wrecking Crew in it, though.)
Black Panther... I'd be cool with Klaw, but he may be used in Age of Ultron, so... Killmonger?
Avengers: Infinity War - Part 1. I think Kang the Conqueror would be cool and is a good guess. Death has got to be in there somewhere. Maybe Kronos.
Captain Marvel. Hrm...could be Moonstone. I'm thinking Deathbird and The Shi'ar will be a heavy theme in her film. But who knows, they may make her down to Earth (pun intended).
Inhumans have to face off against Maelstrom, agreed.
Avengers: Infinity War - Part 2. Gotta be Thanos. With Death and again, maybe Kronos in play.