The real obvious ones include the original and revisited (2020) Pale Blue Dot photos from the Voyager 1 mission. Closer to home, there is Blue Marble (Apollo 17) and Earthrise (Apollo 8).
My favorites are a view of the horizon on Mars night with Earth and the moon faintly visible in the sky (Curiosity). There's also a good one from Cassini that includes Saturn's rings and Earth, but it makes the screen look cracked.
Anyways, I never really think much about this collection, and throw one on whenever I get a new machine. I prefer quiet backgrounds, nothing too noisy or flashy - I've even had solid colored backgrounds for many years.
What do you use for your desktop background / wallpaper?
Black for daily driver(s). Red for encrypted and sandboxed tunnel networks using fascist firewalls. Purple for heavy logging isolated dirty net for monitoring new malware. Green for new installation being prepped as a PXE/iPXE network install image.
I don't bother with using images as the background/wallpaper on my desktop any longer if only because I rarely, if ever, see it because application windows cover the desktop.
https://www.tmahlmann.com/photos/Rockets/United-Launch-Allia...
Having said that, I did get some neat shots of Niagara Falls while on vacation last week, so those are slowly taking over a few of my devices.
Otherwise, flat black
A plain single-color background is the least resource-hungry of background images.
For desktop backgrounds I use either flat colors, whatever I like that comes with Linux Mint, or an image I like from my collection of photographs, which stays until I feel both bored of it whatever I'm doing at the moment. No faces- too distracting.