I'd have to say Coinbase is pretty bad too. From personal experience, a couple months ago, almost every time i've bought at a low, they've canceled the transact

I'd have to say Coinbase is pretty bad too. From personal experience, a couple months ago, almost every time i've bought at a low, they've canceled the transaction because it was deemed to be "high-risk." Prior to that, i'd buy some coins and they'd wait until the price dropped quite a bit to "complete the transaction." And i'd contact them again and again and it would take them a week to get back to me as the transaction was pending.