These are the best apps that will serve and give you more  extensional features than the actual system apps.

1. ES FILE EXPLORER
    Best file manager app with beautiful  features like ricycle bin, checking of ram consuming  apps, archiving and unarchiving of a file.
this app beats the actual phone file manager.

2. RAR or winrarr.
    Enable you compress and decompress  files easily and fast.
   for me,  it's a lil bit  faster than ES file explorer.
Rar opens all type of file extension both 7z, rar, zip etc.

3. WPS OFFICE
     Enables you create your own documents.  both PDF,  Docs, txt, spreadsheets and more.

4. OPERAMINI -
     for easy web surfing.😊

5. UC browser
    for fast download  of files with high memory.