I built a Late Lancaster from TVM last year, and was very pleased with their product particularly their inletting of the lock, barrel and trigger. They do good work, though they don't shape the stock as much as Chambers does, and they don't inlet as many parts as Chambers does.
I am building a Chambers fowler kit now. It may be a little easier than the TVM kit, or I may be more skilled now, but my TVM was better inlet for the lock and barrel than my JC kit. . . So each have their strengths.
I went with TVM because I am left handed, it cost little less and they had more options for me than JC did . . . I was pleased, but I also had a local coach and the Gunsmiths of Greenville book and lots of time on Youtube to help. . and this forum helped a lot too.
If you can afford it, Chambers might be best, but from all I have seen, TOTW, Petonica River & TVM all do good work on their kits . .and I think it's fair to say that a kit Sitting Fox is OK too. (Built is perhaps another matter.)