Coinbase is what I use, but I don't do much trading, only taking my proceeds from my Nicehash wallet and putting them in the Coinbase wallet, which I can then use directly, or convert to USD. Coinbase can only hold Bitcoin, LiteCoin, and Ethereum, so if you are looking to mine and/or trade other cryptocurrencies, you need to find a different exchange, which I can't give you a recommendation for.