I've used many forms for exchange in the past, most of which were average. Out of all those that I used the most suitable and trust worthy has been beaXchange.
They have most of the major crypto-currencies for trading and interestingly enough, they charge no fees for registering and to start trading. Good thing is, it's available on all platforms so I can use it on the mobile as well.
Their commission rate is the lowest I found on the market and it has saved me lot of money I usually agreed to give away on other platforms.
I highly recommend beaXchange (beaXchange.com)