For me, it's a case-by-case consideration. Depending on our chemistry, and my mood, it could go either way. But if a sexy white wife really turns me on, and she has a great bottom, I definitely want to enter her backdoor. Anal sex is extremely kinky, and dominant, and so deeply personal. Indeed, anal can be even more intimate than conventional sex. So, if the vibe is right, and I'm in a very raunchy mood, bend over on all fours, or head down, ass up, arching that spine seductively, and reach both hands back to pull your butt-cheeks apart.
Otherwise, bareback missionary, fucking her pussy feels more ideal as far as the shared wife scenario goes.