If you are going to do only short local trips on relatively flat ground, you might get by with a 1/2T, esp. one of the newer ones with HD payload option. If going longer distances including moderate to steeper grades, twisty roads and lots of freeway towing, you want a 3/4T.
I've towed with both a 1/2 & 3/4T and now tow a 29' TT with an F250. A 3/4T truck is just beefier overall and quite a difference. I'd avoid 4WD unless you absolutely need it because they're higher off the ground and harder to get in & out, you lose a bit of payload cap. due to extra wt. of drivetrain and they're more maintenance. I'd get one with longer wheelbase (extended or crew cab plus long bed) for better handling. I'd also get 4.1 gears for better acceleration and climbing hills. Payload capacity in a tow vehicle is the important number for TTs, not tow capacity. Payload capacities vary all over the map so choose wisely.
BTW, when looking at tongue weights, do NOT use brochure dry weights. Use a min. of 12-13% of the TT GVWR. Some TTs can be close to the GVWR rating fully loaded up, like ours for ex. and some TTs can be closer to 15% TW, like ours.