853*480 for me, it's a 16:9 size. I also use fit Inside and ajust window so my app is fully responsive on every device and take advantage of the different screen sizes.
My frame is set to fit a 1040*640 format, so the app can adapt its screen size to every formats.
For an unknow Reason, using 853*480 on android make some screen bugs on devices that run this screen size, so I've set the original size to 853*479. I haven't found what is the best resoution to use, i use this one because i was used to use it on Windows Phone.
I've also did a picture to show the interest of using a 16:9 format as default (16:9 can fit a 3:2 screen with fit Inside and adjust window option way better than making an original 3:2 app by showing more vertical playground) :