Keaton's batman was experienced and could fight excpetionally well, his fight with the dude with the swords showed this. Keaton's Batman also was a shit-ton more technologically advanced than Bale's. If Ledger's Joker had to deal with the BatWing or a FULLY evolved Bat-mobile he would shit his pants. Also I think that Keaton's Batman was more merciless and would have no trouble killing the Joker if he needed to.