I'm actually using it for my Accessport, but I have a Scosche Magic Mount (Window variant) and it has been working great. Mounts to the window securely, the arm is firm but still adjustable, and the magnet is quite strong. Taken it on several spirited drives and it has held on strong even when pushing the car through switchback corners. The AP3 is magnetic already so I didn't need to use one of the included magnetic plates, but I did test it out with my phone (a OnePlus 3) and the mount felt super secure. I was actually able to slip the plate between the phone body and the case without sticking it to anything and it held up just fine, so you can easily reuse the plates if needed.
$25 on Amazon but I got mine on sale for $19, and it qualifies for Prime if you have it. They have several variants if you don't want to mount to your window, including dash mounts, vent mounts, and mat mounts.