Duke. I have attended multiple games at both sites though.

Terrible parking at UNC. Easy at Duke, but used to be easier when Duke was really bad at football.

Nothing to be done for the seating at Kenan (UNC) Stadium; if you're over 6-2 (I'm 6-4), it will be like riding in an airplane all after noon; your knees will stuck under your chin.

UNC crowds are typically larger, so getting in and out tends to be more of a problem. That said, there are plenty of nice places within walking distance to sit down with your peeps, grab a beer, and watch some sports until the traffic clears up.