This probably shouldn't have been in the Signs and Decals section, so hopefully a moderator will put it in the regular Vinyl Cutters/Transfers area.
Anyway, for being a member of the forum you can request free samples from Josh at Imprintables (check the Exclusive discounts and offers forum). I've used their Eco-Film (plain color non printable) and their Solutions Opaque (printable with solvent printer), both seemed very decent compared to the items I've used in the past. The opaque is a bit heavier hand when compared to Eco-Film, but it gave me a solution for color'ed logos on blacks and darks (use my Brother DTG for lights and some darker colors)
I've also heard good things about
Heat Applied transfer vinyl for t-shirt applications (haven't used em yet though).