Etherdelta is one who you can trust, but always be sure that no one accept them will get your private key! You can loose you money instantly and without any vhance to take it back
Etherdelta doesn't store your keys. It's the concept of how a decentralized exchange works. Even if they got hacked your coins/ tokens are still safe, since they are not with ED.
Apart from the UI the exchange being decentralized is good and to be trusted.
But again I've used it and lost money simply of a buggy interface which mean you should be carefull nonetheless.