Unless I'm in a huge hurry (which I'm usually not), I prefer eating inside. I already go inside to order my food, since I really, really hate using the drive-thru...I figure staying inside for a few extra minutes to eat isn't all that bad.
(Plus it means I have to wait less time to start eating my food, especially for those places that aren't a two-minute drive from my apartment, as I don't like eating in the car even if I'm not the one driving.)