I'll take ...
- the clustering and stability of VMS
- the UI of SunOS circa 1992-ish
- the windowing system being a mash-up of NeWS, X11 and Plan 9
- the consistency of Plan 9
- the frugality with resources of QNX
- the scalability of Irix
- the even-my-mother-can-use-it-ness of iOS and its applications
- the the-hardware-just-works-ness of anything Apple
- the FOSSness of Linux or {Free,Net}BSD
- the documentation of Oracle's databases
- for the filesystem I want to smash together the elegant simplicity of POSIX, the versioning and ACLs of VMS, the databasey-ness that never really made it into BeOS (I understand that OS/400 has similar concepts, but I've never used that), and networkability of Plan 9
I would also like a kitten, and for sausages to grow on trees.