The coolest design in the world is worthless if the shirt it comes on is uncomfortable or doesn't fit right.
At Completely Different Shirts, we do all of our printing on Gildan 6400 Unisex Softstyle shirts. They're 100% cotton with a 4.5oz fabric weight, pre-shrunk, jersey knit, double-stitched, quarter-turned, with shoulder-to-shoulder taping, and tear-away labels.
That's a lot of shirt-industry lingo to say "they're high quality shirts."
They're comfortable. Sturdy. Won't shrink in the wash. And the tags come off easy-peasy (which is particularly important to me, because I hate tags.)
I sampled many different shirt models, wearing them each for two days straight (including through sleep) and the Gildan, for me, fit the best and was the most comfortable. That's why I chose it. I know everyone's shirt preferences are slightly different, but, if nothing else, I promise to never sell something that I don't personally think is a rad shirt.
Gildan recommends the following in order to maintain the maximum quality of shirt.
Machine wash cold, inside-out, gentle cycle with mild detergent and similar colors. Use non-chlorine bleach, only when necessary. No fabric softeners.
Tumble dry low, or hang-dry for longest life.
Cool iron inside-out if necessary. Do not iron the printed area.
Do not dry clean.