Secret Wars makes more sense.
Don't they already have most of the tooling?
Well if it's Secret Wars then yes, the only nostalgia would be that it came with reprints of the old Marvel comic with possibly repaints of existing Marvel Legends characters.
I'm not sure when the series of comic books came out, but since I remember reading it in either 5th or 6th grade (which for me is '83 and '84) I wonder if they have something planned for a 25th Anniversary Tribute to the Secret Wars comic series. It was a great series, it was the first big Marvel heroes/villians cross over series that I was ever familiar with, featuring characters from the Avengers, Fantastic Four, X-Men, Iron Man, Hulk & Spiderman books all facing off on an alien world if I remember right. I'm pretty sure it's also the first appearance of the Black Suited Spiderman.