Afterlight- This one is probably most known because of celebrities or famous people use for example; Willow Smith, Kylie Kardashian, Acacia Brinley.
It's great for touch ups or editing brightening, contrast etc. They also have a lot of great filters, but I don't really use them I use the 'Fade' in the basic editing. But it's probably mostly used for its use of frames as they have lots of shapes: circles, hearts, triangles or your basic rectangle frame (which I probably mostly use)
Photoboothapp - I mostly use this app for a reflection effect or to use the collage, the reflective effect is either horizontal or diagonal.
Papelook- Now this is good for 'Tumblr' like edits as with this app you can add transparent pictures! But to do this you have to save Transparent pictures onto your phone. Easy way to do that is to search 'transparent tumblr pictures' on google search and save them! I still need to get the jist of it so it doesn't look so structured
Hope you found that helpful, if you like this sort of thing then let me know and I will try do more blog posts like this!