Heres the recommended list of bitcoin exchange sites:
https://coinmarketcap.com/currencies/bitcoin/#marketsIts a good list, you can also play arbitrage in Bitcoin from exchange site to other exchange site to get profit.
I didnt know if there was a list somewhere of the more popular BTC exchanges. I have been searching. I found Kraken. It appears to be laid out nicely. Id like to look at a few that allow trading in smaller amounts for someone just starting out.