I've been in the auto repair industry for almost 25 years, and have bought $40,000+ worth of hand tools. I still have most of it, because I bought mostly Snap-On and Matco.
Since my paycheck depended on that tool working right here, right now, the first time and without failure, I'd go with Snap-On, Matco, Mac, or Cornwell.
The lifetime warranty is great, but you have to wait until next week for the tool truck to come back around to get a new one. The good part, is failures are rare and you can always borrow the piece from a coworker for a few days (in a professional environment).
For home use, I'd go with Craftsman any day. The lifetime warranty is great and the price (a fraction of Snap-On, etc...) is even better.
If the thing breaks, you have to stop what you're doing, clean yourself up, and drive to Sears to get a new tool. That's worth what you make it worth.
The only thing I have to say about a direct comparison between Craftsman and Snap-On, is that a Snap-On tool (socket, wrench, etc..) is less likely to strip out a rusty fastener. So when you tackle that rusty bolt with a crappy tool, there's more of a chance you'll damage it to the point where it has to be taken out with a drill bit or a torch, than it would be if you had a high quality tool in the first place.
The bottom line with all this, is how much is your time worth. Period.
With the auto industry what it is now-a-days, there are many mechanics/technicians out of a job. I've seen full toolboxes ($50,000 worth of tools) going for a fraction of what the guy paid to fill them. There are too many out of work guys selling their tools for them to be worth much on the open/used market. The tools aren't worth any less, they're just too many of them to make them fetch the prices they're actually worth. So no....if you're a home DIYer, I would not pay retail Snap-On prices before I'd buy some Craftsman tools. Just find some poor bastard who's been laid off and buy his tools.
Bob
