Which is better? 'Sleep' or 'Hibernate' on a Windows computer?

Turning it off is better - as the computer does some "housekeeping" chores while shutting down or rebooting that it can't do while sleeping or hibernating. If you're going to be leaving it for longer than twenty or thirty minutes (or just installed some updates, even if you're sitting there) - reboot.

Overnight - reboot for sure.

Walking away to answer the door, get a drink of water, or other bio-breaks - your choice.

Leaving it defragmenting the hard drive - make sure hibernate & sleep are both turned off or you'll come back to find that it didn't finish defragmenting while you were away because it went to sleep (or hibernated).

NONE

I never used either one, both under Windows or Linux.

My PC is either on or off, simple as that.

Shutting down only takes two clicks, powering on only takes the push of a button, so why bother with crap like that???

Doing a shut down - restart also clears all RAM and virtual memory, stops any and all programs and apps running in the background, so the computer is faster after restart than if it's sitting in sleep or hibernation.

It is never good to hard turn off a computer by pressing and holding the power switch, especially one with Windows.

Always use the proper shut down sequence.

That is just another one of the many reasons why I never used 'Sleep' or 'Hibernate'.

Sleep just. Turns the screen and hard disk off. Hibernate is where the CPU is still running but everything is kinda minimized and frozen until you start it up again. Then they "restart" and continue what they were doing.