RAM Mount "X" mount.
They aren't cheap. You'll drop about $60 on the full setup, but IT WILL LAST.
When I first purchased an iPhone 6+ I bought a RAM Mount setup. It migrated through 2 motorcycles and now is attached to my Sling with an iPhone 11. Lifetime warranty, modular and I've ridden with this setup on a unfaired motorcycle at 90mph and it holds fine.