Coinbase makes it very easy to interact with crypto. It is a portal to BTC.Sincerely this is how I start using BTC.
GDAX is the best, less to no fees, but it is not user friendly and if you are true to crypto, you need to know how to move around GDAX.
Coinbase=GDAX.
If you have an account in Coinbase, you automatically have an account with GDAX.
Keep on steemin'