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
Gotta say, almost everyone has Binance in their list and why it wouldn't be after seeing its progress around the world. Bianance CEO is kind enough to spread his business around the globe and already talking with the banks to have the fiat to crypto and crypto to fiat option opened up for the world. I guess there couldn't be better option than this and no exchanger is even thinking about it that way. Binance also came later in the time when others were doing well but still it easily caught the market secured its place in top 3. So yeah surely it is the most recommended exchanger and one can always feel free to start with it before even going anywhere.