TFTM gets worse for me every time I view it.

ROTF is by far the worst of them. Watch the directors commentary and special features on the Blu-ray to find out why.

DOTM works OK for me as a "turn off my brain and just enjoy the action" movie. It's still terrible but it is my favourite of them because of that.

AOE I really hate, its a train wreck because of the human parts. The Transformer parts are far better than anything in the other movies, they actually get a tiny bit of character development. I'm getting the Blu-ray mostly because it's a Transformers item, not because I like it.