I also really found myself enjoying Quicksilver. I thought it might be kind of cheesy, but it worked really well. Another thing that worked well was the tension. In comic movies, you know at the end that the good guys will win, so it's not always easy to effectively build tension, but it worked here IMO, with the switch back and forth with the 70s and future Sentinels at the climax. And on both of those fronts, you have to credit the director and editor (and I'm sure Singer played a significant role editing). Is he the best director doing comic films now? Maybe. Nolan was a better filmmaker IMO, but of course he's out. I think the Russos have potential, but you can't go on much with a sample size of one. I think Whedon is overrated, and Snyder is extremely limited. So maybe he is just because I don't know if any really great directors are doing comic stuff right now.
I was making my case for X-Men before, but that doesn't detract from how good Winter Soldier was to me. It had a goal of creating an effective, suspenseful political story with great action and spectacle, and it succeeded on those levels. I totally can get why someone would prefer this to X-Men, as I think it does some things much better than X-Men does, notably the action (the opening scene, the scene with Fury's SUV, the elevator scene, the scene on the bridge, the fight at the end. . .), which makes sense when the great action really does seem to be one of the priority goals of the film. But my personal preference is for the kind of movie Singer put together. Costumes didn't even bother me while I was actually watching it. Nor did other quibbles about whether the story was derivative in some ways. Because right from the beginning, the movie sucked me in and kept me there.