Coinbase is what I recommend for getting money into an exchange. CEX.io is another way to get money in, though when you buy bitcoins with them the prices they give you seem a bit low to me. This is easier to get money in by credit card than coinbase, I'd use coinbase if coming from a bank.

Bittrex is the exchange I recommend, and they have a lot of currencies. Poloniex is ok, it's big but slightly fewer currencies, I don't like the interface as well. Kraken is a bit better interface, but way fewer currencies. C-CEX has a reputation for scamminess and running questionable currencies, I'd stay away.