Big ups to the OP, good thread idea !
Anyway, I found it hard to choose one of the above.
Thor TDW: while I find the big pipe organ palace a bit silly, the rest of Asgard started to take on a bit more shape, but the best and most aesthetically interesting aspects of the film were the Dark Elves and their technology.
Perhaps not completely original, but I liked the look of Malekith and co, their tech just looked evil.
Man of Steel: I loved the organic tech look. I think I would probably rate this one above TDW, just for the reason that Krypton was a refreshing change from previous films - if you go frame by frame through the Krypton flight sequences you see the incredible level of detail they put into Krypton, which is not surprising (I know a guy who works at Weta, and they did that part of the film, and they are nothing if not meticulous).
Guardians of the Galaxy: Has to win, as they covered several different culture-specific aesthetics (the bright-shiny look of Xandar, the strange segmented appearance of Kree tech, the cowboy feel of the Ravagers and of course the junkyard look of Nowhere ). All in all, it was nicely done - and I believe a reasonable rival to Lucas' work on Star Wars - for some reason the locations in the prequel films never looked believable to me, whereas GOTG actually looked much more tangible (maybe they invested more in sets ?)
Regardless, I enjoyed GOTG for its action and humour and those were nicely set against strong background visuals. The image of the Milano entering the giant floating celestial skull to the tune of David Bowie, is not one I'm likely to forget anytime soon. It really did create a sense of wonder -something that's been sorely lacking in Sci-fi movies for a long time.
Yeah, Interstellar was great, but the tone of the film was such a downer - although I did like Nolan's representation of 4th dimensional space !
So GOTG wins, for me, in the end. GL , well I try to forget as much as possible about that film, but I will say that the 2013 animated series did a better job of creating an overall aesthetic and interesting alien environments.