3-link:
pros
- you can keep your gas tank in the stock location
- no bed modification required
cons
- a bit less flex than the 4-link (but still lots o flex)
4-link:
pros
- lots o flex
- simple, tried and true design that most vehicles are running
cons
- you'll have to move your gas tank since it's in the way of the links
- you may have to modify your bed
I also heard that with less than 3" of lift, or more than 5" of lift, the geometry will be off.
Regarding the quality of TG's stuff, I believe it to be great quality. Yes, they use chinese steel, but I think it's plenty beefy, and well-made.