for now the better on in my opinion should be
https://etherdelta.com/.
it's decentralized exchange,what does that mean ? we're directly selling our coins to other people.
we do not need to verify our account and we just need to import our account directly then make a trade in there.
indeed it's a bit complicated in the beginning,but if you use it frequently you will be get used.
actually it's very easy and everything is based on the network.
Bittrex.com and
Poloniex.com lately made a shady activity,
i believe some of you ever heard about blocked account and we need to verify it even though we're already have a basic account.
seems like they want to track us down by using our document.
Kraken.com has no problem with it,but their system/technology is terrible.
we can not make a move or order when the market make a quick action or sudden action.