Your not go really feel happy with doing socks. I use liner socks or adidas socks that I get from ross. They come out nice but not perfect. I Just deal with it. No matter what you will get void lines. It seems the thinner the the ribs the better.
The De Facto sneaker fiend/AAU club ballin', spoiled pre-teen and teen standard in sublimated socks is the Nike Elites. Lucky for anyone sublimating the Nike Elite is 62% polyester and with Nike's stronghold on the shoe game at all levels its a no brainer. The Adidas equivalent, Team Speed crew, has only 17% polyester, 59% acrylic, 20% nylon, 3% natural latex rubber and 1% spandex. All that said, the Adidas isn't a wise choice for sublimation.
Cutting to the chase. Head to Champs and grab a few 3-packs of their branded Champs Sport Gear aka CSG crews and you won't be disappointed. They are 98% polyester. You can't get much better than that for the price you'll be paying.
But if you gonna use Nike Elites stop flossin at Ross cuz you ain't neva gonna find Elites their. Trust me I stay in the streets shopping. The best you'll get at Ross, Marshalls, T.J. Maxx, etc. is K-Swiss or Under Armour. The K-Swiss has the Elite striping up the back while the Under Armour doesn't. Both are comparable for sublimation but again, "they ain't Elites" (in my Kanye voice). For practicing I suggest you still comp a few pair to use as your testers. This will save you some bucks as Nike Elites aren't cheap unless you catch footlocker slipping on the buy one get half off sales. And stay away from the Nike Outlet for Elites too. If you want customers to respect your product don't use those blems or irregulars the outlet offer. Unless you put it up front to your customers and cut them a break price wise.
That's about it. Hopefully you find your sock(s) and start churning out some product you feel comfortable presenting to the buying public. Good luck brah!!.