I use both of them and I would say that paypopup have better payout, but high min payout. Adversal have better tech (at least pop under) and low min payout. Paypopup also have lower min UV per month requirement (5,000) then adversal (10,000). Which one to use is what is more important to you.
So far I personally prefer paypopup. Which one you decide is entirely up to you, but there are better ones than both paypopups and adversal.