IJ180 ... its the best. But at $1 per/sq foot + lamination... its expensive if you screw up.
IJ35 ... its cheaper and almost the best.
I've used Oracal and Arlon and found that the adhesive will delaminate from the top surface sometimes. I hear that General Formulations has a 10 year calendared that is cheap and very nice...but I haven't tried it yet.
I also prefer not to stock 50 different types of digital print material (although I probably have that many).