These are all in competition.
1 Poloniex (Supports all cryptocurrencies)
2 Bittrex
3 Bitfinex
4xBTCe
5 Bitmex (High volume with many less known Cryptocurrencies available as well)
6 GDAX (Part of Coinbase)
7 LocalBitcoins (Decentralized exchange)
8 Kraken
9 Bitstamp
10 Coinsecure (Indian Bitcoin Exchange)
11 Huobi (Chinese exchange)
12 OKCoin (Chinese exchange)
13 Gemini (Trusted & popular)
Will be preparing tutorials on all.
Keep up the good work.