Here's my list:
1. Linux (Debian and Arch)
2. Amiga OS 3.1
3. Sparta DOS X 4.42
4. MyDOS 4.53
5. MSXDOS 2.41
6. MSX-View 1.20
7. Residos 2.25
I've only listed OS's I currently use. I've used MorphOS for 7 years but not anymore, if I would still be using it I would've listed it in second place.
