Really ? Do I have to say it for the 1000 time, do not keep your funds in an exchange , you are not in charge of your bitcoins this way, they can go offline and lose all your money, they may restrict your account, they can do anything to you if they feel like it. Use a desktop wallet or hardware one, and do trading with little money to learn first, if you are successful add more money, but withdraw directly after trading to your desktop or hardware wallet.
If you use bitcoin you need a place where you can access your coins fast and not only at home, so an exchange is needed. And yes i believe coinbase to be an ok exchange