I think one platform might not suffice for trading if you are planning to trade whole lot of different coins. Not a single exchange has got all the coins listed, so you will need to use multiple exchanges in such case.
As others have suggested all exchange have got some specialty so based upon your requirement you can choose them. Or give some popular exchanges like bittrex, kraken, poloniex, bitfinex, binance, huobipro, etc try and you should be able to figure which one suits you the most.
I have requested an account in Bittrex, until now it hasn't approved yet.