The answer depends on how you intent to use the sat nav.

On the phone I use an app called Here - its free and has total EU maps. But the phone isnt as good as a proper sat nav having a tiny screen and a small speaker and short battery life with gPS running.

For the bike I use a Garmin zumo . Several reasons. Its waterproof. It works by blue tooth as well as speaker. You can edit routes on the PC with a nice big screen and download them which is great if you want to drive some particular scenic twisty road.

If I were buying a Morgan I would use either Garmin or Tomtom and I would use a blue tooth earpiece because you will never hear a phone speaker above the wind and engine noise. And you dont want to be peering at a screen whilst spirited driving.