Well, you're entitled to your opinion and I agree on some points (Browning, Goode, the fact that Snyder is more of a visual stylist than an actor's director). But like many other posters, I feel there have been numerous great performances in Snyder's films -- particularly Butler, Haley and Cavill.
With Cavill in particular, I'm not really interested in whether or not he gave an "Oscar calibre" performance, because that's not necessary in this role. The challenge was to look and act like Superman, and Cavill absolutely embodied the character to the point where I don't feel like anyone could have offered a better performance than he did. The role of Superman isn't showy anyway.
I do have to take issue with your assessment of Ackerman's performance as Silk Spectre II, which seems a little hyperbolic. This is something I read in a lot of reviews of Watchmen, and for the life of me I can't understand people's criticisms. I'm not saying Ackerman is Meryl Streep, but I'm puzzled why people think it was such an awful performance. For me, she embodied the character, looked and acted the part and was perfectly convincing in her emotional scenes.
But really, this seems to be a problem across the board with superhero movies. Unless your name is Emma Stone, it almost always seems to be the female lead who is dismissed as the weakest link in superhero movies, often singled out for dismissal while the male actors win critical accolades. What I think this overlooks is the fact that the female leads in superhero movies are almost always saddled with the thankless role of "love interest", and there's only so much you can do with that.
Amy Adams is a good example. I thought she was the best Lois Lane yet, and yet a lot of people seem to have a problem with her performance when if anything, it's the screenwriting that would be more at fault. In that case, we should criticize Goyer, not Adams (of course, the point is moot if you're not a fan of Amy Adams in anything).
Anyway, I'm pretty confident Ben Affleck will offer a great performance as Batman. Snyder can do the dark vigilante thing (Rorschach), while Affleck was fine as Daredevil (whatever you thought of the movie itself) and is a huge Batman fan. So I'm not worried.