[Senusret I]

There are other people here more qualified to give you the answer, so I will instead pose a question:

Why can't you and the guys in other fraternities just be friends?

Edited to add: I mean, I find myself surrounded by Sigmas and even enjoying their company, especially since I'm just sort of "okay" with a lot of the Alphas in my area. But I don't think that leaving Alpha and pledging Sigma would solve anything, even if it was allowed for NPHC orgs.

And I'm pretty sure that the values of most fraternities are broad enough where they include pretty much anyone. It sounds like you just get along better with men of other fraternities better than your own, rather than the values of the fraternity not being what you thought.