Well, if all I towed was 10K I might consider a 2500. Gasser.
A lot of people feel that a 1500 is more than enough for towing, but I am not one of them. Having towed from 1,5K to 65K I have developed a feel for what works well in real life (not J2807 ratings).
Again, 3K behind a TRX, okay, but...