Have had Discover since 1989 and really think it's been great. No problems ever, always get an email when it's time to accept the next quarter's specials on cash-back. Easy, easy method to manage any disputed transaction, US-based customer service, so I don't have to try to communicate with Mujibar in India. No complaints. 

Had had a GM Visa for a while, mostly b/c Visa was all Costco would take, and we got the extra points to use at the GM dealer, plus there wasn't any transaction fee if used overseas. Then they switched website hosts and configuration, and it became the most user-unfriendly damn thing I'd had to deal with.

Canceled that thing after a bit and got the Capital One Mastercard. It's been really great so far.  Now I don't have anything to use at Costco, but I'm more of a Sam's girl anyway. And still no foreign transaction fees, so that works too. Points accumulate and can be transferred straight to a bank account or used for travel.