Weight is the first thing we check. Anything under 240gsm drapes badly and shows every seam after a few washes, so our tees start at 250gsm and the hoodies sit closer to 400.
After that it is the knit. Ring-spun yarn costs more than open-end, but it is smoother, takes ink more evenly, and does not pill around the underarms after a season of wear. We have yet to find a shortcut worth taking there.