It's f stop,has unique features not found in others and is regularly updated --

1.custom sort photos scroll position and zoom of each pic
3.lock position and zoom

Similar apps i tested are -- gallery plus,a+ gallery,dv gallery,ai gallery,simple gallery pro,gallery no ads,gallery picture gallery,
gallery pro,gallery365,gallery hd.

I completely think and that too at once and work,therefore u can't go wrong with my app suggestions.
Lot of patience.