I use Oracal 651 (shiny, outdoor and craft) or 631 (matte, wall), and like those the best of the ones I've tried. I get mine at
www.hhsignsupply.com , and if you like their FB page, they run specials. Just Friday they had a $5 shipping day. Their regular shipping is pretty fast (they are in Kentucky), but the $5 special takes a bit longer. I don't mind for just $5, though!