I'm a big fan of over the belly undies, personally. :P And, I'm super cheap, so I just buy undies in a bigger size than normal. I'm talking like 3-4 sizes too big. And, if I need bigger, I'll buy bigger when I get there. Something under my belly just drives me crazy. Maybe it's because I had a cesarean last time, or maybe it's my big old fat belly, but they never feel like they're sitting in the right spot under my belly.
If you have a hard time finding 3-4 sizes too big, try plus sized undies. Just My Size is the brand I buy. Very comfy, and 3 for $6 instead of 3 for $15 like most maternity panties I find.