Not a single Exchange will work all the time they all have there problems if you juist want to buy crypto's and hold on to them I suggest you transfer your funds to a wallet.
Hard wallets are the moster secure but they cost money (Ledger nano s, trezor)
Well, you did a great job of not answering the question there. And since I have been looking for the same answer, I'm going to call you out on that.
The OPs question was not about holding or anything like that, it was about an exchange. Yes yes, we all know we should HODL.
But for those of us who want to have a more active participation, we'd actually like to know the decent exchanges.
Putting the question back out there.
FYI: GDAX = Coinbase, as far as I know....