I currently use Simple Gallery. While it is not bad, the UI could definitely be better. I tried Aves for a bit but it seems to not have a built in photo or video editing feature which is a deal breaker (unless there is a version with those features?) Any suggestions?
Seconding Image Toolbox, it’s awesome! You can convert between image types, resize/crop, draw, do background removal (basically manually erasing parts of the pic to make them transparent), it has a nice collection of filters you can apply, and it even has a color picker.