I've used both, and like others, I'm more concerned about the location of the site, space around it, and the views around it than I am about whether its paved or not.
I do prefer gravel or dirt, though, all else being equal. Just feels more rustic and more like true 'camping' that way, which is why we do this. When parked on pavement, it feels more like we're in a traveling condo and not really camping. I know some prefer it that way and I definitely understand the reasons why, but its not my preference.
DW is the exact opposite, though. She prefers the concrete sites because our kids track in (and play in) less dirt that way. Every time we camp at places where you can chose between concrete vs dirt, she pushes me to get a concrete site, but amazingly, the concrete sites are all taken when I make our reservations. Just seems to always happen that way.
Will & Angela
2 children that love camping, Stephen & Allison
2012 FR Georgetown 351DS on F53 (V10) Chassis Our Rig