I used to be a full-time auto mechanic back in the 1980s and my perspective was this:
Craftsman tools are good but in some cases, they are not as durable as Snap-On, Mac, and Matco. The durability issue really shows-up on sockets; Craftsman sockets were much more prone to cracking and rounding-out when used on a daily basis. Back in the 1980s, the Craftsman tool boxes were not nearly as good (sloppy drawer movement and the tracks wore-out quicker) as the "Big Three" and they didn't have really big boxes. Craftsman has improved considerably since the 1980s on tool box durability and variety.
Snap-On, Mac, and Matco are really popular with full-time mechanics because the tool vendors come to the mechanics, the mechanics don't have to take time out of their personal lives to go to Sears after work.
There are some cases where it is an absolute must to have Craftsman tools. Flare nut wrenches are the best example of needing Craftsman along with the "Big Three". I ran into many situations where the "Big Three" all made their flare nut wrenches with a specific orientation of the box end such that when in cramped spaces, you could loosen a flare nut fitting but you didn't have the room to rotate the fitting enough to reset the wrench to loosen it some more. The Craftsman flare nut wrenches had box ends that were rotated by only about 15-13 degrees but that made all the difference. You would loosen the nut with one wrench, then slip in the other brand name to loosen some more, switch back to the first wrench, and so-on. The process goes slow but you know how it is; auto manufacturers do not design the cars with the intent of being easily serviced.
Mr. Spindlelegs
