Does anyone know which airline has the best mileage program? I have been with American, but it resets every year and I have tried Delta, but I can't earn miles unless I book on their website and not with my travel credit card.

Best depends on where you live and where you fly to. I have friends who swear by Alaska Airlines which does me absolutely no good. Miles on an airline you wont use arent much value.

For me AA and UA have the best flight options, and I have a credit card from each of them. AA Citibank and UA is Chase. Each has certain advantages.

There are some good mileage offers out there from many different airlines. I saw one recently. from Delta/AMEX for 80k to 100k bonus miles.

All of the US-based programs (plus BA) have moved to $$ spent basis and away from mileage so they are all about equal (equally bad ) So as J62 says, 'best' depends on the one that is best for your home airport and/or your main destination airports. If you live near one of the 'fortress' hubs -- like DFW for AA, ATL for Delta, DEN or ORD for UA that is a big part of he decision.

None of them are all that great without using their branded credit card. I mostley fly AA/One World -- simply because that is where I first made status and have almost all of my miles/loyalty points and I'm sort of tied to them. Unfortunately this year I probably won't make platinum so may become a 'free agent' and fly whichever has the best fare. I don't use an airline branded cc - but probably should think about getting one . . .