I'd go for the Bahamut-SIN fight
This link claims it to be Bahamut Tremor after the japanese fighter planes, its Bahamut SHIN in japanese. http://en.wikipedia.org/wiki/Bahamut_%28fiction%29, but it could be wrong since everyone calls him SIN.

My favorite battle would have to be the highway and tunnel chase, best chase scene in any movie I've seen in a long time.