My experience/situation is a little different from most guys that are in the trade, simply because I'm a collision guy.
I have a fair amount of Craftsman bought 20-25 years ago, a bunch of Matco stuff, a little Snap-on, and maybe a half-dozen Cornwell.
My boss when I entered the business was a die hard Snap-on guy. He said I'd be sorry buying Craftsman because if I needed to get it warrantied, I'd have to take it to a Sears store (which at the time were everywhere, and one was on my way home). I guess he liked waiting a week for the truck to come by.
But, the real reason I bought Craftsman was a long polished combination "professional series" wrench set from Sears was $80, and included 7-19mm. The snap-on set was $339.00 and included 10-19mm.
I'm a body guy. IF I was a mechanic, I might have bought the snappys, but honestly, I have never had a complaint about the Cman set. BUT, I don't use them as much as a mechanic would. I use them a lot, but most of our stuff is where a socket and ratchet will get 'er done.
Of course there are some other names in the box...Lisle, K-D, gearwrench, mostly for specialty stuff.
I guess my point is: consider the use that they will see, and buy accordingly.
My junkyard box has a mix of stuff that was bought cheap at pawn, or donated/found stuff
Last thought, if you're going to buy off the truck, the driver/dealer makes or breaks the experience. We had a GREAT Matco guy and the Snap-on guy was a dick at my first job. Currently, we have a good Snap-on guy, a pretty new Cornwell guy that seems like a good guy, and are getting a new Matco guy after the first of the year, haven't seen his predecessor in like 5 years, despite calls to his cell, emails, and requests through the website.