Well, I fly with whatever airline offers me the lowest fare to wherever I'm going. When I have a choice - ie, when the fares are the same for Delta, American, United, Midwest, Northwest - I choose the carrier with the fewest connections and best times to fly. Most of the time, it's not American or Delta - they have fewer departure times from my nearest airport (MKE) and the times of day for flights aren't what I am looking for.
I've also started making my decisions based on the aircraft types on the routes I'm taking. After spending 2+ hours in an EMB-145 to Houston on Continental last year, I vowed I would not fly in that aircraft on a longer sector again, because it was very uncomfortable. I try to get an aircraft with full-sized seats and at least 2-2 seating.
Where food is concerned, if I can get to San Diego for under $300 round trip from Milwaukee, meal service is not too important to me. I've been spoiled by Midwest when I've flown them, because they are head and shoulders above every other carrier in terms of service and comfort for the money you pay for a ticket.
If American wants to eliminate food service on all of their domestic flights, let them. Personally, I don't think their nasty bistro bags or pretzels necessarily make their flights better or worse. However, they will run into problems on routes where other airlines offer a meal. American will need to reduce their fares to compensate for their lack of meal service; I don't see that happening, so the likely outcome is they will lose customers.