I use about 5 different exchanges, and Bittrex is my favorite in terms of user experience. Clean interface and easy to use. Some of the smaller exchanges offer niche coins and various benefits, but the learning curve is high. For example, I recently used EtherDelta to buy a niche coin, and it took me hours watching youtube explainer videos to figure out how to use it. At times, the cost of time can outweigh the benefits. I never had issues with Bittrex but the account suspensions make me feel uneasy. Best to always keep most coins in the wallets, but I always keep a fair amount in the exchanges for trades. I'll check out BitShares for sure, hope it's user friendly! :-)