Bruce is no slouch. He built just as many Kryptonian weapons to fight them off as Lex did. And whatever Bruce didn't come up with, he had someone who was more knowledgeable do it for him.2)Luthor is a genius. Einstein, Hawking, Da Vinci... dunces in comparison. Batman might challenge Lex at chess, but in the lab Batman would still be trying to light his bunsen buner while Lex had built a transdimensional space-time viewscreen out of a bathroom mirror, some aspirin and a razor blade. When trying to beat an alien who survives supernovas, a fancy boomerang and a bad attitude are trumped by an understanding of quantum physics.
Even Lex has failed to get the job done, despite all the time spent on it. So long term prep time isn't the solution.3)Lex exists to kill Superman. It's what he wakes up planning each day and his last thought before drifting off to sleep. All the genius in #2 is focused only on this goal. Batman spends his life trying to defeat multiple opponents- his attention is not fixated on any one of them. In short even if they had the same resources Lex devotes them all to one goal, Batman doesn't so his resources left to defeat Superman would be less.
Again, Bruce went through the same steps to take down Clark than Lex has. Both had access to Kryptonite. Both studied the effects of the red sun on Clark. Both even built weapons.4)Lex has yet to succeed. I'll give Lex the nod between him and Batman as having the better chance to defeat Superman. That chance is like 1 in a gazillion, but it's still better than Batman's chances unless you remake Batman into a Superman-obsessed villian.
They are allies, but in previous continuity, Clark had done some stuff that truly scared himself. So much so that when Clark got a hold of Lex's Kryptonite ring, he gave it to Bruce to use on him, if he ever went rogue. It was a sign of trust on Clark's behalf. That after several years and some tense moments, he was willing to let Bruce be the one to pull the trigger. This is what lead to Bruce creating the JLA protocols and subsequently Brother Eye.Originally Posted by The DarkNut