I don't recall all of the battles and cant' say there would be a favorite, but I have a number of favorite scenes.
"Sacrifice of angels" two parter has a few of them:
*  The ending when we saw a shot like we've never seen before (at that time) in Trek:  A huge fleet of Starfleet ships (and that awesome closing score cue to go along with it).
*  Part 2:  The ships moving in an engaging, and the fuck yeyah cool scenes of Galaxy class ships giving it to a Cardassian vessel.
* Seatac and Majestic destructions.
*  The Klingons coming in to help and laying it on the enemy fleet.