We've also had success with Stride Rite's seamless socks. You can order them online.

We have seriously considered moving south so that sock season is shorter.

I buy Jeffries seamless socks on Amazon. It is the only sock she can tolerate and does not seem to have other sensory issues.

My DC is 17 and still uses SmartKids socks

Everybody has their thing. If you're looking to buy online, many websites that sell occupational therapy products also sell clothing, e.g.,:
https://funandfunction.com/seamless-sensitivity-socks.html

We use smartkids seamless socks. He suddenly this year at 5.5 did not want the elastic thread in the crewsocks. Smartkids are expensive but no more arguments!

Although she's not otherwise SN and doesn't display other sensory issues, my 7-year-old is my second child to have major issues when it comes to socks. (Hysterical meltdowns ever morning, etc.) I bought some seamless socks at Nordstrom for my older child when she went through this (from about ages 4-8) but as I recall, they only came in a style that had a folded cuff-- taller socks-- rather than ankle socks. Does anyone know of another good source for socks without a seam across the top of the toes?