Till I have use many file managers but out of them which I found more useful and effective is Es File Explorer File manager .The thing I like most is it thumbnail feature which make it easier to explorer the contents.the another best feature of this file manager is that arrange and categories all the same kind of contents together( like all the movie file in movie folder, music in music folder, app in apps folder etc).The another best thing is that its homepage give the complete overview of you files and contents.