I don't normally even check that, I just reboot it just in case after an "apt full-upgrade".

I shut it down completely and enable "Deep Sleep" in the BIOS, as any planeteer would do.

It depends. Some laptops have quickcharge ports which are still powered even when the device is turned off. Some offer control over this via a BIOS toggle.

Seeding / torrenting a little (very little) and playing youtube radio mix low volume while sleeping myself these days. Turning it off when the lights or sounds in my room annoy me too much to rest.

When I know I am not going to use it for a long time, f.e before going to sleep I shut it down completely (desktop machine), my laptops (work, personal) I usually just close the lid and let them hibernate.

My advice is have your HDD spin down after about 30 minutes of inactivity and shut down your machines when not using them (shutdown, hibernate or sleep) this will make the hardware last longer, HDDs are more affected by this action.

I have one "server" machine that I used to just leave running and the HDDs spinning 24/7 because I was using them quite a bit, many of the HDDs crashed within 5 years, I now have them spin down after 30 minutes of inactivity and they have been running fine for many years now.

Also it is cheaper on electricity, it does add up.

Back when I had my previous PC with a normal 7200 rpm hard drive I would leave it on during the day because it would take several minutes to do the startup process (because it was old) but now with a ssd I usually turn it off if I know I'm not gonna use it for a few hours because the startup takes less than 30 seconds.

close the lid

Modern hardware can use very little power on stand-by and suspend mode. Going from memory it started back when Apple advertised suspension (C6?) would last weeks or months on a battery charge. At that time had 2 old 10" Asus eeepc netbooks, older one last something like a full day on battery while suspended, while the newer was involuntary tested at almost a week and a lot of battery remaining.
Modern power supplies must meet some criteria in order to meet some standards, one of them is very low power drain in off mode (actually all home grade devices must have very low stand-by power).
My current desktop draws 1W when off and ~2W on suspend mode. The mini-pc draws less than 1W on suspension.

I have my computers set to suspend in 10-20 minutes and only power them off when not in use for long times.
The desktop can go for weeks without being turned off while the mini-pc has a strange problem that it correctly suspends 3 times after reboot, after those 3 times it turns itself on after 2-3 seconds of being suspended,

Over the years I've had 3 laptops that randomly soft-locks on suspension, all with ATI/AMD video cards.

Windows 10 seems to do a few things differently from Windows 7. So...

If I am working on something that requires several programs and projects to be available, I find myself using Sleep very often. It is fast and serviceable.

Else I wold turn the computer off. Apparently, for Windows 10 “shut off” involves a bit of saving to disk in a sort of hybrid behaviour with Hibernate. Then, if you always shut it off, apparently it would be good that you use “Restart” now and then, if you want updates to apply.

Hibernate has. been deprecated. Used that in the past with other computers, but with a large amount of RAM, it seems to put some stress on the hard disks. Apparently that is the reason that this option is not available by default (as you probably know, you can still enable it).

So, to sum it up, more often than not, Sleep. Otherwise, Shut Off. This, with Windows 10. With other OS, just plain shut off. With older hardware, Hibernate used to be an option as well (rarely, but I preferred it to Sleep).

Turn it off. A 14s cold boot with a modern SSD and 0.5w powered off power draw makes it pointless to just leave running for the sake of it.

This certainly holds some truth, though in reality it never happened to me - at least not yet. I've been unplugging it daily since 2009 and CMOS battery was never discharged. Nowadays, i spend most of the time working or doing relevant IT stuff on my laptop (Linux), so i'm only using my desktop (Win 7) for gaming or music recording (10-15 hours per week).

So, i guess it can happen when a PC doesn't see much use in general, or maybe if the battery is already old, though in practice with moderate daily use i don't think it's a common occcurence.

I shut it down and unplug it.

As was mentioned there are several options available to keep it running and save power. One of which is hibernation mode. This, though, has a massive impact on available disk space ... One of the first things I disable via command prompt powercfg -h off It can easily gobble up 100 or more GB which you certainly got better use for. I sure do! That is not to say that one can't set the size one's system is allowed to use. With this command line argument powercfg /HIBERNATE /size (size in percent) 25 (for instance) it is possible to limit it.

The important question to ask yourself is whether it is worth to keep your system up and running when there isn't some important task in progress. When there isn't, shut it down, safe power and money. ;-)

It's better to spend the extra money on power and wear the computer out faster than to turn the computer off so you can save those few seconds? Okay.

When I've finished using it I shut it down. If my husband wants to use it I'll just logout. If it's doing something time consuming like downloading or if I'll be coming back to it in a few minutes I'll just leave it.

When we go to bed I switch the plugs off at the wall.

If we're staying away over night or there's a thunder storm I pull the plugs out too.

It won't "wear the computer out faster", because it's in sleep mode and there's no activity. And it's a lot more than "a few seconds" to boot from a HD. (There was also the notion that the power usage and wear/tear from cold booting was more costly than sleep mode, but I don't think that was ever confirmed.) Do you understand the difference between a HD and a SSD? The second one is much faster. Since getting a SSD I've usually been shutting down instead of sleeping since the boot time is way less annoying.

The difference isn't nearly as great as you're suggesting. If you're in that much of a hurry, you must have quite the exciting life. Also, leaving something running as opposed to not leaving it running will wear it out faster. Do you understand the difference between using something and not using something?