In my opinion the best ad networks for those ad formats depend on the type of traffic your gets in part.
But I would say
for capped popunders
Fastclick, Tribalfusion, and Popuptraffic
for capped popups
Popuptraffic
for CPM banners, tribalfusion, fastclick, and burst
for strictly CPC banners Clickxchange, Clixgalore, maybe Valueclick
If you are talking about uncapped popups or popunders different adnetworks are good at this sort of thing.