What is the best program/app you have installed?

Always interested in what people have found, and could be used by others.
For me, the best ever program (which has got me out of many a foolish move) has got to be Macrium. The times I have done something very silly and major happens from time to time. Good old Macrium has been an absolute life saver.
What do other recommend?
C

My most used programs (other than explorer, browsers, email client.. ) have to be
Poppeeper (mini email client I use for scanning my accounts very quickly and handling emails, but sent via Thunderbird)
and
Roboform - password manager

I like Volume2 - very neat, scrolling control of volume on hovering over taskbar e.g. - other options available.

Actual Window Manager (or cut down Actual Titlebuttons) - adds buttons for many things on most title bars for e.g. on top, recent files & folders, favourite folders.

Qttabbar - colours explorer-related backgrounds, adds features to file explorer including tabs

I bet the OP is gonna get a ton of answers, and none of them will include UWP Apps!!!
Sorry Mike Rowsoft!

I bet the OP is gonna get a ton of answers, and none of them will include UWP Apps!!!

... - there's got to be one... surely... please someone??

Edwin said:

Programs I can't do without:

• Good PDF program
• Top notch email client
• Cent Browser
• Good image manipulation program
• Good video/screen recorder program
• gotta agree with @dalchina on the QTTabBar thing - indispensable!

You forgot Music player ,,,, Can't be without that.

My most used program is VLC