Assuming you have the Blue that costs money, then the Amazon cards should be used at restaurants and drug stores for the 2%, but the Amex should be used at gas

Assuming you have the Blue that costs money, then the Amazon cards should be used at restaurants and drug stores for the 2%, but the Amex should be used at gas stations and department stores for the 3% and of course grocery stores at 6%. For the stuff that doesn't fall into those categories though, it's all 1% so either work.