If you are new to crypto trading, and looking for a platform to trade, here are some platforms I use.
Share with all of you

1.
Binance (Strongly recommended)
2.
Bitfinex (Stable, not many coins available)
3.
Bithumb (
ps:security issue happened, consider well)
4.
Upbit (Korea exchanges)
Welcome to other suggestion

*******Additional information************
Recommended by FlamingFingers :
Bittrex - 2 years exp. and No issue ever
People who use many exchange is swinger and that is good strategy in in this situation. I start use swing at August, not always profit but I can make big money when market not balance again. I recommended Hitbtc and Kucoin as alternative Binance and Bittrex, easy to use and have friendly support team.