I've been using coinbase and cex.io recently. They have too much of a fee in my opinion. Anyone use gdax, or what does everyone use?
There are many exchanges out there. Personally I use these 3 exchanges, Bittrex, Poloniex, and c-cex.io and fees are not much here in my opinion. They are much easier to use when it comes to buying altcoins but it would be hard if your money is from fiat so just bear with coinbase for buying bitcoin from fiat. I have never used gdax, the one you mentioned so I can't suggest it.