Are you sure about that wide range of altcoins? Trading sites that doesn't organized well their coins list will just give their users increase the chance of losing. The most trading exchange that really have a wide range of altcoins is Yobit exchange. Since their commencement of operation, Yobit is quiet on the bottom list of good and trusted exchanges by most users in the community. You can check the volume there and test the risks if you want.

Crytopia, Bittrex, Poloniex are some of the trading platforms that have wide range of coins to be traded. The good thing here is, they are delisting coins that doesn't established a good volume within a timeframe . Because of this, it won't mixed to other alts that have a good daily volume.

Actually you are the one who will choose an exchange. There are lots so you want might to check them one by one. Sounds hassle but in that way you will know what's fit your criteria.