AppMgr III

Manage your Apps, Move your apps between SD card and device memory, can also manage APK files

SD-Booster

(ROOT USER ONLY) Speed up your sdcard and memory up to 40 times! You can also speed up by freeing up more space by transferring files and data between your smartphone and PC. List all your files by type,etc.,

ES Task Manager (Task Killer )

Frees up memory
Helps clearing cache
Clean your RAM
View your device info
Check or diagnose various problems in your smartphone, can also freeup unused memory using a widget.

ES File Explorer File Manager

Free to use, Simple interface with a lot of features similar to ES Task manager.
You can all files separately with type such as Images, Music, Movies, Documents, Apps.
Recycle bin feature
Also manage files in Google drive, dropbox, Amazon Cloud Drive
Multiple selects, Select in between, etc.,
Can backup apps as apks
Network, SD Card, Download manager,etc.,
Cannot access sdcard and delete files

I use File commander

Can access, manage and share files both on device and remotely.
Convert files between various formats
Also manage files in Google drive, dropbox, Amazon Cloud Drive
Can access sdcard and delete files

Popular Apps(Cleaners/Boosters/Antivirus)

AVG Cleaner
AVG Antivirus
Clean master
Android Booster Free
Easy Battery Saver
Battery Doctor
Avast Mobile Security
Apps Freezer

Disclaimer:
All the sites listed above are from my knowledge only, and I have heard about some but won't them or I haven't even visited some of them. I am not reviewing or rating any of those, Just passing some information I know. These sites may not be permanent and may be changed or closed in future. I'm not responsible for any loss you can have using this websites, so use with caution, Thank you.