Portal2 is a weak version of Portal1. The story in Portal2 isn't particularly engaging, the puzzles are interesting but suffer from incredible repetition. The atmosphere is really its strongest point, but I think DEHR does atmosphere just as well.
MW3 is COD and is crap because of it. It's a guilty pleasure, not something you hold up as the pinnacle of game design.
Batman AC will probably be a pretty solid contender and I'll reserve judgment until it's actually out. Based on what I've seen of it I wouldn't put it leagues ahead of DEHR
BF3 is a similar story to Batman but weaker.
Skyrim is probably going to be the main contender actually and it really comes down to how bad the quality at launch is