Hi can you good people help, we have a stand alone trucknav which has in the last 2/3 outings gone a little off grid, I.E. down a couple of narrow'ish roads, not got stuck "yet" but you never know, so i was wondering if all the funsters out there that use the nav apps which in your opinion is the best, paid for or free , thinking of getting a new tablet to use as a sat nav possible the samsung tab A 10.1 with a sim card slot so i can have data only with whoever has the best deal ,or do i bite the bullet and get the Garmin 770( it's a which best buy ) at 250 + , over to you.