I have been using Gifs for those small loading images. Have been working great except the occasional transparency issues and 8 bit colors. Now I found out about the APNG recently. But don't know if i should be using it. Does it have enough browser support? And what about the file size. A large gif image already has large file size...
Answer
I think APNG is better. As it supports 24-bit and 8-bit transparency. Moreover it is also supported by browsers like Mozilla Firefox, Chrome, Safari (see https://caniuse.com/#feat=apng).