I’m kinda poor, so I can only choose between the 6, 6s, the 6/6s plus, and the se.
That’ll be contingent on what phones the beta testers use
There was another thread that talked about this
I’m sure you’ll phone will work great with the app
Some phone with a good processor and high RAM
It depends what iOS they support because some apps require a certain iOS
You don’t need the best phone to make videos, but I know what you mean… the best doesn’t alway equal better quality, I have a 6, I used to have the 6s+ but it was just to big… get a 6 you’ll love it, and it has a good camera.
Samsung Galaxy S9
The Razer Phone
I would advise you to get something by LG, probably the LG v20 or the Google PIxel, but that’s not an option Your best bet is probably the 6 or 6+. The camera is nearly the same as the 6s at a lower price point. I have a 6+ and if you want to see some pictures I took with it: