AA or United?

If you had a choice and prices and times were simular flying from the US. Would you use AA via Miami or United from Houston? I haven't flown with United in years.

Edit: thanks for all the reponses. United it is!. I am flying from DFW and the day I want to go there is not an AA direct flight. AA has stuck me in a roadside hotel in Belize once overnight and an 8hr delay coming back from T&C at CLT in recent years. I don't fly often but I have earned more miles from AA from their screw ups than any other way. I will try United this trip!