Do you mean print onto the vinyl, or cut vinyl, as it can be overlayed.
Many suppliers offer garment film, xpres seem to be the cheapest and there really isn’t any difference in any of it that I have found except the premium flock/promo flock, and that is minimal.
For choice of colours go with xpres as far as I have seen they have the best range across the board, if you want to overlay use superflex or easyflex, you can overlay ultracut but its thicker and will show more, but is more durable with tumble drying etc
Ive had stuff from a few suppliers and as I said best and cheapest is from xpres, target transfers do the same sort of range and I have now got them down to the same price as xpres for any length but it was a long struggle.
I had the rep from target down and he gave me some white T shirt transfer samples that can be printed onto and when pressed feel more like screen printed transfers than the plasticky ones xpres do (ink jet dark etc) ring them and ask for a sample, I’m sure they will send one.
It wasnt as hard wearing IE stretching as the xpres one but felt a lot better
hope thats useful