all these options don't come in one package.

for example the biggest volume comes from poloniex and i suppose bitfinex next. but neither of them are reliable. poloniex services and specially their support suck. and bitfinex is the one that got hacked last year and people lost a lot of money, not to mention all their troubles with the banks and all the stuck money!

then comes the trust! how do you even trust these services? most of them don't respect their customers enough and change their rules without prior notice and like always there is the risk of their "hacks" /s