Ooh, this is a tough one... they're such different films, but at the core, both aim to do the same thing: reintroduce a legendary hero a few years into their journey and kickstart a new cinematic universe.
Honestly, my preference could change depending on the day. Both are definitive takes on their characters—it just depends on whether I'm in a Batman or Superman kind of mood. That said, either one is far more rewatchable than anything that came out of the Snyder-verse.
For me, The Batman (and soon, Superman once it hits HBO Max) have joined the ranks of the DCAU animated movies and series as go-to rewatches—those used to be my “at least they got the characters right” comfort zone. Thankfully, Reeves and Gunn have captured that same spirit in live action, each in their own way.