I will vouch for the cornwell bit sets, they are made by VIM as I was told by my dealer. I own the biggest one they make that I bought on sale for 200 bucks, and it has been so handy and durable I never even considered Snap Ons "sale" price of 700 bucks, I have used both, I prefer the Cornwells.
The only time I broke one was when I put a T50 on my 1/2 impact to remove a flywheel. It broke in 2, didnt strip or strip the bolt.
For the price they are miles ahead of anything you get from craftsman, their bit sockets ****, and for about half the price of SO, with what is in my case better service (great Cornwell dealer), I had to get them. He exchanged my broken one right away.
I am a Heavy Duty Diesel mechanic, work on a lot of Deutz and European equipment engines (Mercedes Benz) that 90% of engine fasteners are either Torx or Hex, I abuse the **** out of mine ( cheater pipes galore) and they are just awesome, have paid for themselves over and over again.