First of all, you had characters like Caesar, Lanius, Vulpus, tales of The Burned Man and even Lucius(sorta), all with their own unique backstory. Their characters were much deeper than anything I ever saw while siding with the NCR, they had better personalities, and they had much better voice actors. Every person I met in the NCR was the same thing...Corporal, or Major such and such, with no standout characters at all.
Assassinating the President was much, much more fun than protecting him. Just taking out a sniper, a mechanic and then waiting for the speech to be over? Please, dressing up as an NCR Trooper, sneaking in and taking out the president, and walking off like a boss was a lot cooler. The ending? Much better on the Legion side, sure Lanius was a much better final boss than Oliver, (Obviously), but infiltrating the Hoover Damn, fighting Power Armored Soldiers and Veteran Rangers galore made for a much better final battle. The main reason being because taking something over is much more fun than shoe-ing some soldiers away like in the NCR ending.
So regardless of whether or not I agree with the Legion's ideals and methods, playing through that side of the story made for a much better experience. Anyone else agree?