Only problem with iron-ons brady is that they start to crack and peel after a couple of washes. Using the paper, you'll also find that the ink will fade.
If you have a motive try a few of the screen printers in your area as this process impregnates the material with colour which does last longer. Failing that embroidered ones which are best but expensive to set up for short runs unless you use a ready made design that the manufacturer has in their software
Been there, done it and got the T-Shirts lol
Dave