Hmm the final battle in Dragon Age was pretty epic for me I was really looking forwards to it however I feel they should have included more tough darkspawn in the journey through Denerim sure there were plenty of ogres but I wouldn't mind having seen less Grunts in the horde assaulting the city, grunts are fine but they die in a single hit if you train so sure it looks like you're killing a surreal number of enemies however they're 1hit kills I think if they'd increased the numbers even further with the normal darkspawn and added extra grunts in to boot so you're truly, truly killing in epic proportions.

Other great boss fights I remember include General Shepherd on MW2, from the suicide insertion through to the knife throwing ending that was one hell of an epic finale (though I agree it has a lot similar structurally with the ending of CoD 4 in fact I would dare to say it was the same structure of infiltration, chase sequence and then slow-mo finisher and a different formula would have been nice)

The Ace Combat Series has always made me take a deep breath before the final mission because I know to expect something insane what will test my flight skills to the very max. I have yet to be disappointed by their insanity or design. Generally the flying at around 50ft at high speed through a tunnel so tight that the slightest miscalculations results in a game over screen is something reserved for the boss battle in the game the final mission however in Ace Combat 6 they used it I feel too early and too often throughout the game so when the final battle came there was no surprise it would be expected here as well I remember in AC04 I entered the final mission and honestly felt my jaw drop slightly and my eyes widen as they commanded me to do that I thought "hell is that even possible?"

Along similar veins the old Colony Wars games had good final missions too and Front Mission 3 and Vagrant Story Hell Vagrant Story had one memorable boss after another really.