What about House? And Yes Man/Independent? Well, they're not directly opposed as the Legion and NCR are, but I feel like it should be decided, or meaningless debated without either side actually agreeing.
I wild carded my first playthrough. Didn't much like the ending, as it was, y'know, anarchy. And Yes Man "changes his personality"? Suspiciouuuus.
Mr House is a bro. I've been warming to him as best choice overall, really. Even if he does just care about the Vegas. So yeah, House.