I also have a discover card but it sucks now since they decreased the % you get back. Plus I think they limited the 3% cash back to the first $250 you spend. Anything after that, you get 1%
Depending on how much you charge a year, the American Express Blue Cash card may suit you. Everything you charge you get 1% cash back, but once you reach $6,500 in charges then you earn up to 5% cash back at supermarkets, gas stations and drugstores, plus up to 1.25% cash back for all other eligible purchases.