Do not use Coinbase! They have extremely poor service and will not support you if you ever encounter issues logging in. Instead, they will write a generic response to your ticket and immediately close it. If any major bank tried to pull this they would get buried in lawsuits.
Again, avoid this service at all costs. Forget their greedy 5% fees on deposits/withdrawals - it doesn't even matter if you can't get your BTC or USD back period. That's a 100% fee.
What problem did you have with them exactly? If its about the login, I can remember that they always require their users to always confirm the login from their email before the login will be allowed. I think thats part of their own security process, though it can be very frustrating at times cause it randomly misbehaves.
And like you have said, they hardly reply mails they are sent. They do reply but not all the times and I think they dont reply to issues they think are not really worth their reply, something they think you can sort out yourself. But Im not the type that can abandon my money for any exchange, Im not that stupid.