Her latest incarnation is only two years old, so it might be surpassed later on, but in Fifty Two she is tossing a human through the air while crushing the jaw of a mutant fish-faced crocodile creature, inflicting an injury that "the Batman himself would think twice about before inflicting." That is not a quote from a fanboy or reviewer, but of an actual comic author who has written Batman.
And from Batwoman #0, after being ambushed by Bruce Wayne in disguise as a Secret Test of Character, she kicks him in the face and makes him bleed. Sure it was a set up, but it was still awesome.
The moment when Kate, feeling like everything is pointless, completely lost and without a purpose... looks up into the sky and sees the Bat Signal. I could hear the Danny Elfman Batman theme swelling to a haunting crescendo even as I read that bit.
Her final battle against The Weeping Woman has Kate literally confront her demons and come to terms with her sister's death.
Medusa's completely invaded Gotham and is basically unleashing hell when Batwoman returns to Gotham with Wonder Woman in a Big Damn Heroes moment
The Grand Finale that is issue #17, and which really should have been named "Batwoman Does Many Awesome Things."