I've preferred bars with center knurling in the past when my weight training actually mattered for something. Something wide enough that I could see it on either side of my neck, those were my favourite bars for squatting as it made it easier to get a symmetrical set-up under the bar before loading it's weight onto my back. Now when I am able to get into a gym, I just use what's there and have never been worse off for it.
So..... personal preference/kinda doesn't matter?