A lot of people think Kevin Conroy is the best Batman. It is not hard to see why either. In the animated series, Arkham games and other appearances, the voice actor really crafted a stoic voice for that character that endures today.
He is only one in a long line of actors who have taken up the cowl though, and in a recent interview with Screen Geek he talked about his favorites of those. In particular, it seems he is a fan of Christian Bale's Bruce Wayne (maybe not so much his Batman), and also gave a kind shoutout to Ben Affleck too. He said:
Each actor brings such a different art to the character, it's really fun. I think Christian Bale's Bruce Wayne was probably the best Bruce Wayne. I think the voice he used for Batman was bizarre. [As for] Ben Affleck, a lot of people gave him a lot of crap for getting cast. People on Twitter were going crazy about it and I said, "Wait a minute, wait a minute. Give him a chance." I think he surprised a lot of people. He's really wonderful. He does really well on both Batman and Bruce Wayne.
It's always interesting to hear Conway's opinions on other 'Batmen' as he has probably been with the character the most. He probably should know.