I think these shirts are dope. I'm hoping some crew necks come back in stock soon. As for the topic of branding, this distinct style does a lot of the work for you, but having a simple logotype to go along with it wouldn't hurt.
American Apparel blanks with zippers on them, nothing special... good for you that people are actually paying for it while you can easily make it yourself for a lot less. Nothing wrong with zippers, but try and make some cut 'n sew pieces with a nice cut and fit instead of using regular blanks.