My desktop has a Samsung 840 pro 256GB, I got it because I wanted something fast for my OS and to be able to hold some games and programs that I use more frequently. It also has a 1TB WD Black since I wanted a drive with some storage space but still relatively fast and cheap.
I have two external HDD's that i use for backups, storage of videos and other random files.
My laptop has a 750GB HDD of some sort, not entirely sure what it is but it's very slow, would be nice to get a SSD for it. I have it because it came with the laptop.