I personally think The Avengers cinematography is absolutely legendary. Whedon and McGarvey created clear, bright, colorful and natural image, which greatly supports and enhances what's going on in the movie. No heavy color filtering, when the whole movie begins to look like it consists out of 1-3 primary colors. The image isn't over-saturated either. Fullscreen aspect ratio is greatly appreciated too.
Trent Opaloch is close second. Or maybe I can even swap him and McGarvey, but since he was the first in MCU, he takes the spot. Opaloch and Russos, it seems, continue the tradition of The Avengers, but their image is while even more natural, a bit less saturated, colors are slightly more muted. But lighting setup and camera work are close to perfect in my book.