As someone that didn't grow up on Keaton, to be quite honest I find him to be the most overrated Batman. Even moreso than Affeck, because at least with Affleck it's a bit of a popular opinion to say he could've been better on a few places.
I mean, I like certain things about his portrayal (such as the way he said "It's just something that I have to do) but man do I think it doesn't hold up at all to scrutiny, his Batman was 100% reliant on cinematography.
Bale I think will hold up because I completely, 100% believe him when he's under the cowl. Does he have ridiculous lines sometimes? Is his voice garbage? Yes. But in scenes like the Flass one, in scene like the Joker interrogation, he still disappears into the role, any shred of how he performs Batman outside the mask is completely gone and I completely believe his anger, I believe his frustration, I believe he's now transformed into this other creature. The body language he exhibited in the Joker interrogation scene, I mean that was brilliant and made me believe him as Batman. That was never the case with Keaton, his goofy faces and the way he spoke always gave him away. And I still don't buy him as Bruce Wayne, his look and the "Let's get nuts scene" summarizes why. He did fine, but I still can't help but look at other actors from that time and think "What would've been?", that's not the case with Bale, Bale was undeniably the best choice for the part when he got cast, Keaton was just a weird one for the sake of weird.
Affleck I'm really, really torn on because I remember really liking his portrayal when BvS came out, but upon rewatching I can see how certain things could've been better and again, he was completely reliant on cinematography for Batman, and I can't really say I ever saw him play Batman with how altered his voice was.
Conroy still remains the best Batman by far to be honest. Yes he's a voice actor, but it's his performance that made me, in the middle of the 2010s, become a fan of Batman. If he still holds that kind of influence after voicing the character for 20 years, then I honestly can't deny he's the best Batman. I think that no matter what year you first hear Conroy's portrayal of Batman, he still has a sort of influence and impact none of the other ones have.
Pattinson has potential. But I hope he does his own thing and not just rehash Keaton like many want him to do here. I honestly think Pattinson has way more in common with Bale than he does Keaton, but I still don't want him to rehash Bale either. Let him come up with something unique but still distinctly Batman. And honestly, I don't believe in that whole "Well Bruce Wayne is the most important part of the performance", it is important, but so is Batman, and I'm glad that whenever Pattinson talks Batman he talks about how to approach it inside the suit.