Bet. If your opponent was calling your flop bet with top pair, then you will hear about it now on the expensive street when he raises. But if your opponent did not have top pair on the flop, he might fold, fearing that you have made trips. Checking would be bad against one opponent, because you are telling him that you are drawing, and he will know to stay with you. It is a lot harder to bluff the river successfully if you check the turn.