Taken from https://cryptocurrency.market/faq/, although I personally have only used coinbase.com. I suggest you check out the rest of their website and their youtube channel "https://www.youtube.com/user/PrisonOrFreedom/about".
- What exchanges are reputable that you guys have personally used & tested to buy or sell bitcoins using fiat currencies such as USD, EUR, JPY, GBP, etc. and you don’t care about privacy?
♦ www.Coinbase.com
♦ www.GDAX.com
♦ www.Gemini.com
♦ www.CumberlandMining.com (For block trades >$100,000 USD)
♦ www.Kraken.com
♦ www.TradeBlock.com (We use the aggregate BTC price for our block trades)