>Kaypro 10
You should sell. I have no idea how rare it is but it might fetch a decent price among retro collectors.
>Dell Latitude
Install Windows 98 on it and make it a DOS/Win9x era retro gaming machine. Or keep it stored somewhere and hope that in 5 - 10 years it will increase in value with retro collectors. Or throw it in the trash.
>HP Pavilion desktop and laptop
These machines still have pretty decent specs for basic use, and can run Windows 10 or current Ubuntu / Mint just fine. You could turn one of them into a HTPC or living room web browsing machine. You can try selling them for about 100 bucks each, but I'm not sure it's worth the hassle. If not, donate them (i.e. to a school or some poorfag who is in need of a working PC).