Quality of Crew necks?

[WeLoveMusic]

i wanna know what type of crew necks are these like material example: 80/20 etc etc

http://www.cmonwealth.com/products/crooks/medusa-crew-blk/medusa-crew-blk.jpg

http://www.cmonwealth.com/products/10deep/livelarger-gry/livelarger-gry.jpg

http://www.cmonwealth.com/products/acapulco/mcmspitcrew/mcmspitcrew.jpg

and just by opinion if your know which crew neck sweaters you think is better.