I am very fond of candy cam for the past 2 years now. I am using one plus 3 right now, and this app works perfectly in it. It is really good for taking both pics and videos. There are more then 30 filters in it for both photos and videos.
In candy cam you can also edit pictures in your gallery, the editing in this app is very cool, it contains many rare feature like making hip slim or wide, making your smile big or small etc.
The app is just around 60mb, and it is completely free in play store, so dont hasitate to download it.
The only problem with candy cam is that you can take good selfie pics, but not good group selfie in it. Coz it has auto vignet in it. Thus making only the centre of the screen bright and the remaining pretty dark. The picture clarity is good, but we cant take hd pics.
But above all this app is one of the best camera app for android, I would highly recommend you to give it a try.