The trailers for the GOTG films were amazing, especially the Vol. 2 "Fox on the Run" trailer. They were fun, energetic, and full of personality. Honestly most of Marvel's trailers impress me, the Thor: Ragnarok and Spider-man trailers were also great.
The first Rogue One trailer blew me away. (it just occurred to me that Rogue One, a spinoff, has the only trailers in the Star Wars franchise that I actually consider good - and Star Wars is one of my favorite movie franchises.)
The teaser for the first Hobbit movie was great and very atmospheric despite not being thrilled with the final product.
The main trailer for Pacific Rim. Honestly, I think it's a near-perfect trailer, the music really ramps up and gets us excited, and it straight out sells the premise of the movie like an advertisement should.
Don't hate me, but I enjoyed the teaser for Transformers: The Last Knight, if nothing else for introducing me to "Do You Realize" by the Flaming Lips. The movie may have stank (although I can't judge, I didn't watch it), but as a trailer, this is closer to what I want and expect from a Transformers trailer as opposed to, say, the marketing for the 2007 film.
I know there are others, but those are a few that come to mind.