I drive an f-150 supercrew short bed with the fx4 package and it's not that bad. I've never towed anything over 3k so i guess my opinion might be void for this. I can say Ford pick ups are very comfortable and great DD's. My mom owns an 08 supercrew 4x4 and it tows significantly better than mine. My uncle owns a 1/2ton Dodge and i felt like the rear end was getting pushed at every turn, and i don't like the way Dodge 1500's sit.
-If you are looking for a DD/Tow rig, get a nice Ford or Chevy 4 door. They sit very comfortably and get decent gas mileage.
-Something that's mostly a tow rig but will get driven a fair amount, go DIESEL!