RangerUp: Not JUST the Americorn, this long-standing veteran-owned gang puts out some epic parody and military tees. Checkout their bounty hunter set, and the Revolution Dogs. Hit the banner when you get there for 15% off.
Teespring: the least expensive shirts with decent print quality. The "Next Level" basic tee is an excellent quality cotton tee, but the print is lighter. Their tri-blend tees are kind of heavy, and print is much stronger. Imported fabrics.
Redbubble: Just decals and beverage vessels of all of our things. I've never ordered their shirts, but the setup and design interface for them sucks. So, just stickers here.
Zazzle: pricey, BUT the American Apparel Basic Tee is made in actual AMERICA. Print Quality is pretty good, sizing is on point. If it only shows one design on click, tap the "products" tab above that...