Android has a lot of file explorer in PLAY STORE among which ES file explorer is the best according to me for several reasons.
It has a clean UI design and very easy to use for a simple user having all the necessary stuffs required for a file manager but it has also many advances features for power user.
I have been using this application for over a year now and have not installed any other file manager.The home UI has a catagorised icons for music, video, apps, documents, images etc.
It has a recycle bin which helps in recovering files that are deleted accidentally.It also has root explore for root users who want to tinker into the system files.
It comes with cloud feature and network access within the home network where I can access file from my pc to my phone and stream videos easily.It has file hiding feature, a built in music player and junk file cleaner.There are more features I am still discovering and honestly this is by far the best I have used and I recommend this to everyone.