It's personal preference.
I think white out looks good, until you go off road or parallel park. After that they will probably look scuffed and/or dirty.
I have white out because tire store chose for me. They didn't ask what I wanted, and I didn't think to tell what I wanted.
I have had them in mud, but they still look good. However rocks, stumps on trails, or parallel parking will make them ugly soon.
Black out wouldn't look as dirty or scuffed.
Warning: I'm notorious for making a post, then editing same post several times, adding info each time, or correcting typos.