Honorable Mention: Star Fox 64 - Katina
Star Fox 64 was the first game I owned for the Nintendo 64 and I played the ever-loving hell out of it. It's funny because, if you're really trying, you can get probably complete a playthrough in around half an hour. Despite that though, I couldn't even begin to make a mental tally of the countless hours I spent playing that game. I explored every nook and cranny of it, won every medal, unlocked the hard mode and then did it all again. I looked up the top player score in Nintendo Power and beat it. Then I beat that score. Then I did it once more for good measure. Most of the time, I don't consider myself all that skilled of a gamer but I have no qualms about saying that I was great at Star Fox 64
My favorite mission in the game? Katina hands down. An total rip-off of the final battle in Independence Day, the whole level is basically one big air battle between the robotic forces of Andross and the defending Bulldog Unit. You and your cohorts in the Star Fox squadron have to help the defenders push back the enemy fighters and destroy a giant saucer ship before it can settle over the planet's base and annihilate it with a giant laser beam.
Most of Star Fox 64 is a very linear, on-rails and scripted shooter. Katina, meanwhile, gives you free reign to fly where you want while also pitting you against enemies who move and fight with more freedom. Add in the fact that you can accidentally kill your allies in Bulldog squadron ("Fox! That's one of ours!) and it all adds up to a battle that's unparalleled in terms of sheer chaos. The only reason I don't give it a proper spot on the list is the fact it's land-locked and not technically a space battle.