Saw "Room" last week. Impressed with the performances of the two leads (Larson and Tremblay), but I found the movie more to just be a bunch of connected "segments" and it flattened the emotional journey a bit. So... not really a contender anyway IMO for Best Pic; good movie, not great but just driven by two great performances.
I liked Revenant a lot, but if I had to list the "best" aspects of that movie, it would have been (1) Lead Actor, (2) Director, and (3) Cinematography. (Hey, look at that!) Would those three things bump it up to also win Best Picture? Apparently not. I can't speak for the merits of Spotlight yet; I grabbed it on Saturday but haven't had a chance to watch it yet (same with Bridge of Spies). Most of the other non-winning pics are on my list as well, it's just that if you missed them in the theater, they are finally now coming out on legal disc/stream and so weren't available until after award season.
I'm glad Leonardo finally won, I think his work has really shone over the last ten years or so; but realistically there are many other great actors who have been up for awards and still have never won. He wasn't even at the top of the list of "most deserving," based on FiveThirtyEight's review of the situations of other comparable actors...
Does Leonardo DiCaprio Deserve An Oscar? An Interrogation. | FiveThirtyEight
I did see The Danish Girl. Another case where there were two decent performances (Redmayne and Vikander), which along with the consistent "tone" led to it being a decent -- but not GREAT -- movie as well; Vikander was definitely the high point, consistently, of that movie. Her performance in "Ex Machina" was on par as well, but the Academy went for The Danish Girl role; I guess having one genre movie (Mad Max) in the runnings was surprising enough and they couldn't muster up another scifi pic.
Honestly, I am just happy that Mad Max was up for so many awards, and not just costuming or makeup; we actually had a post-apocalyptic film in the running for best picture, best director, and so forth. People actually took it seriously. Which they should have; it was an interesting blend of genre trappings, feminism (in what looked like a "men's pic"), and relentlessly streamlined focus. It was both meaningful AND highly enjoyable. (That crazy crimson guitarist could be the high point, image-wise, of Cinema 2015 for me; that was WTF hilarious.)
...Of course, then we've got the issue over the nomination process. Sigh.