Assuming you are looking at 2nd gen and up trucks (the 1st gen trucks are great, but don't hold a candle to the towing prowess of the 5.7l, IMO), in general I've seen this:
- 07-08 were completely new and had a few bugs to work out. Some early years has torque converter chatter, a very small batch of bad cams (if it's still running now, it wasn't affected by that issue), and a few very small growing pains
- 09-13 were generally very robust; they have occasional cam tower leak (not as bad as it sounds, basically a lower valve cover leak but requires a ton of work to repair as the entire valve train needs to be removed to repair since it is dual overhead cam). Mine has been weeping for 100k miles and hasn't dripped a drop of oil. Toyota also adhered to the J23somethingeruther towing standard and the tow capacity came down a very small amount, so you might find some small discrepancies in tow caps between the years. Realistically, any 07-21 5.7L truck will pull 10k lbs, properly set up.
- 14 saw a few changes as the front clip, bed sides and interior changed. The cab and doors, frame, motor, transmission, suspension, axles, etc are identical to 08-13 with a few very minor tweaks to the ECU tuning (mostly for fuel economy but also to dampen the pedal a little as some earlier model owners complained about a jumpy pedal. They lighted the truck a little bit for about 100 lbs more payload (not GVMW, but payload) compared to 07-13. The other big change was the transfer case; same gearing and operation, but different transfer case so it uses a different fluid. Also, the 4wd computer changed so the transfer case is one of the few things that isn't compatible with earlier trucks.
- 14-17 remained largely unchanged with a few additions like the TRD Pro model in '15, the 1794 Edition with rustic leather seating and accoutrements, and a 38 gallon fuel tank in certain models in 15 or 16. They had a bad batch of fuel pumps around 15 but I wouldn't let that be a deterrent. If the truck is still running, it's not an issue. If it becomes an issue, fuel pumps aren't to bad to do.
- 18 introduces Toyota Safety Sense 2.0 or 2.5 (don't recall which) but the ECU is completely different and you get a host of "safety" features such as lane departure warnings, as well as auto-adjusting cruise on some trims. They also started deleting the factory transmission cooler, so beware of that if you want to tow. It's not terribly difficult to add transmission cooler, but I HIGHLY recommend having one installed. My tundra sees temps around 212 towing, my sequoia (without the cooler, but also 5.7 and tow package) sees 230 on the freeway without a trailer. EEK! So 18-21 are little different than previous models for those reasons.
- 22 was a complete redesign. EVERYTHING is different; TTV6 motor, 10 speed transmission, coil sprung, different axles, smaller cab, bigger overall dimensions, different cab configs... EVERYTHING. The TTV6 does an admirable job towing, I'm told, but they are working through a major engine recall right now. Also, the chassis is stiffer and stronger (marginally), and rides a little better, but doesn't load as well (more squat with less weight) due to the inhering nature of coil sprung suspensions.
IMO, my truck is just about perfect for a towing and hauling - which is what I bought it for. I'd look for a '10-17 5.7L 4x4 (if that's a need) with tow package. Cab and bed configuration as you need, but the double cab 6.5 bed gives you the ability to carry up to 6 people and still have a usable bed. You can get a DC 8' bed, but the Crewmax (big rear seat and doors) only comes with a 5.5' bed. The regular cab comes in both 6.5 and 8' bed, but are harder to find. The tow package gives you 4.30 gears vs 4.10 standard 5.7L or tow 4.6L. It also gives you the large rear axle (10.5" vs 9.5"), transmission and oil coolers, beefier suspension, and the best payload numbers.
If you want a solid tow rig, I'd look at installing a set of E rated tires, some suspension aids (air bags, add a leaf, Sumo, Roadmaster Active Suspension, etc) depending on how much you tow and haul, and some better shocks. I added airbags years ago and they have worked exceptionally well for me. I also have a modified leaf pack, but the air bags alone will get it done if you need. Bilstin 5100's are a great bang for the buck but there is a giant rabbit hole to fall down when it comes to suspension.
Oh, and a supercharge will put a smile your face
But it's not strictly necessary...
