We use Orajet 3951RA with Oraguard 290 laminate for these. If the customer specifies the signs are for short term use, we use Orajet 3651RA with 210 laminate.
We use the 3951RA because it's the best cast vinyl Orafol offers and since we do a good amount of vehicle lettering/graphics, it's one cast film/lam that covers all bases, with certain exceptions of course, like low energy surfaces.