I voted black and I'm running black Mickey Thompson Classic 3s on the JK. As with so many things automotive related for me, it all depends on the look one is trying to achieve. There is nothing "wrong" with either finish. Beauty is in the eye of the beer holder. If your rig has no other chrome or polish, you may not want the contrast of the chrome/polished rims. Conversely, if all of the other accents are black, then black might make the most sense. I think on a Jeep the black rims look most "business" but that's just my opinion. When you're talking beadlocks, I like that black allows you to have body or contrasting color ring and that look doesn't work as well with polished. Again, my opinion.
My current Jeep sports my first set of black rims, and I'm sold. Looking to change my black/black suburban over too. I just love that you can't see the brake dust!