i use simple because it's the only gallery i know of that supports apng
but i probably would anyway. i like the standard material 1 design, it's faster than aves, and i don't need all the blur, animations, and eye-candy that's aves' draw. perhaps i'm getting old but simple gallery just works and works the same as all the other apps in their suite, and conforms to standard android paradigms
I dislike simple because according to Play Store reviews their Calendar Play Store version basically blackmailed customers into paying (if they wanted all their data to remain)
It was a one time failure because of Paid versions transition. With calendar you could export your events to ICS file and import to paid app. Or install this app from GitHub or F-Droid π