I dread most of the ones I'm looking forward to as much as anything.
GotG 2: The first one was really fun but suffered from too much exposition and a boring villain. I have a feeling this one will be an improvement. (I'm also looking forward to the other Marvel movies, but this is the one I'm most interested in by far.)
Alien: Covenant: Ridley Scott is still a good director, and I didn't hate Prometheus, but I hope this one has a more comprehensible script.
PotC 5: I liked the first three and thought the fourth was mediocre at best. This has been in production forever, so hopefully they used the time to make a movie that lives up to the first few.
Kingsman 2: This is the only franchise movie on this list that I actually have confidence in other than GotG. The world needs more over-the-top Bond parodies.
Dunkirk: Christopher Nolan + World War 2 + not a franchise movie = yes.
Valerian and the City of a Thousand Planets: Hopefully, this will live up to the legacy of The Fifth Element. Luc Besson doesn't have a perfect track record (looks at Lucy), but when he's on top of things, he's one of the best writer/directors out there.
Blade Runner 2049: The original movie is a masterpiece. Sequels to masterpieces are often mediocre-to-terrible and suffer further by comparison to the original. But they hired a talented director, so I'm not completely without hope.
Darkest Hour: Gary Oldman is playing Chruchill. That alone is reason enough for me to get excited.
Star Wars 8: I really liked TFA in spite of its issues, so I really hope this is a return to form after the disappointing Rogue One.