Affleck.
I supported his casting from the moment it was announced, and the fact it was even remotely "controversial" is exactly why I ignore fandom especially when they get into hissy fits over casting without ever giving the candidate a chance at face-value. He was literally coming off Argo, my favorite film of 2012 where he not only directed and produced with such expertise but also gave a career-best performance in the lead.
So I wasn't "ready to believe," I was automatically convinced. But... I didn't buy him as a Bruce Wayne in his late 40s/early 50s whose cynical, beat down and hard-assed having spent 20-odd years secretly fighting crime in the criminal underworld of Gotham.
Adding stumble and putting grey in his hair doesn't automatically add layers to the performance I'm afraid. You have to see it in his face and he was just too baby-faced for what they were going for. Had they gone for closer to Keaton, a la a Bruce Wayne/Bats experienced and a couple of years into it, which is what I thought they were going for, sure he would have rocked it for me.
He's getting way overpraised here and even getting credit for doing things "for the first time onscreen" which isn't remotely true, like doing detective work and his body-movement.
If he's your cup of coffee, all power to you. But for me he was miscast for what they were specifically going for in this iteration of Batman.