After trying out YoBit,I'd want to start marginal trading.The usual bitcoins to alt and vica versa.The site must be very supportive,less document requirements and supports most of the altcoins.
Also I will be day trading at times or invest in a stable alt for a week/month.My main concern is support,they trading website must support most of the alts and definitely bots.
If you are looking for exchanges with stable volume and supports lots of alts, you can check Poloniex and Bittrex. I used them both and I can say that both of them are really good exchanges. Poloniex has margin trading and I thin has the most volume for altcoins. You can also try Bittrex but just for normal exchange trading because they don't offer margin trading. If you want to interact with other traders, Poloniex has troll box where you can chat with MODs and traders alike. Go try them both and see what suits your needs.