In my absolute expert opinion... Binance. And I say that as a Cryptographcoinager. Trust me, I'm an expert.
Po.et has potential, but I'm not sure on it, but that being said, I'm a follower, so if the clique says Poe, then Poe it is...
How about NXT? It may be due for an upswing, but I would only suggest short term with this one.