I never played D&D and am not familiar with a lot of the nerd lingo, but isn't there like lawful good and chaotic good and things like that? I assumed that the NCR and Ceasar's Legion were basically that; two sides the same coin and all that. I mean, they were both fighting the same enemies (Raiders, Powder Gangers, etc.) and had similar ambitions, as broad as they may be. The Legion's solution was just to murder people and control them by fear while the NCR was just trying to heavily police the mojave wasteland. But yeah, the Legion was too cunty. The first time I met them in Nipton, I must've quick saved, murdered them all, and quick loaded three or so times. Fucking assholes finally walk out of there all smug.
I dealt with the legion quite a bit despite siding with the NCR heavily at first (since I didn't go to the strip right away). The secret to staying neutral is to take advantage of the broken mechanics. I'd run into an area, free the slaves, turn on a stealth boy, then teleport far away. I'd get points for the NCR without losing them for the Legion. Eventually I had to choose a side, but at that point I already dealt with the Legion enough. I don't really mind missing out on locations and quests because you chose a path. I think that stuff comes with being an rpg where, unless you cheat, you can't specialize in everything.