Williams (USA) sockets are very good and typically the best pricing is from Tools delivered:
http://www.toolsdelivered.com/38-Inch-Drive_c_2652.html
Williams was an independent company that has been around for a long time - going back to the 1880's
http://alloy-artifacts.org/williams-supercompany.html
I don't know exactly when they were purchased by Snap-on, but they are part of the "Snap-on tool group". Williams tools are not the same as Snap-on. Within Williams tools, you can have items made in the US or items imported from Taiwan. While the Quality from Taiwan is likely pretty good - I can't say for certain as I only have US Williams sockets (among others). You can tell the C.O.O. difference with Williams items as the Taiwan items have a numerical part number (31943) whereas the ones produced in the US are alpha-numeric (i.e. MSB-12HRC).
Williams was frequently sold through industrial distribution and as far as I can remember, never really had a lot of visibility.
In terms of quality, if Snap-on is the best socket made (arguably), you're getting about 95 % of the quality for perhaps 25% of the price with Williams.
I'd put Proto right up - between Williams and Snap-on as well. Armstrong (when they were around) was about the same as Williams
Depending on what time period your Craftsman stuff is from, you may have surprisingly good quality to middling quality. I know my Craftsman stuff from the 70's and 80's was top quality and a stone-cold value.
I've worn out a lot of Craftsman tools, but didn't want to get them replaced by something made in China and like you, I felt the need to "upgrade" in the last few years. I have a hodge-podge of SO, Proto, Williams, Armstrong, Bonney and even some Taiwan sockets from OEM.
I've had the chrome peel off of Craftsman as well as Snap-on sockets and the occasional Proto. Chances are good you will be hard-pressed to break any of them. If you feel you need or want additional sockets, buy what you like and can afford. If you use your tools for a living, you will be fine with Williams, Proto or Snap-on.