What OS besides the main OS options for Amiga do you use? Please answer the poll and post here about it.
I use two OSes outside of AmigaOS on a daily basis: the various BSDs and IRIX.
I admire BSD as opposed to OS X or Windows, or even GNU/Linux because like the original AmigaOS, they provide you with a well-tested, minimalist OS that you can expand how you want. BSD has three added advantages over GNU/Linux, including:
Better filesystems (ZFS is supported on Free and NetBSD)
Open licence scheme
More conservative and stable
I don't care that X11 has shortcomings compared to other display servers, because I use the bare minimum of graphical programs to run the system, and because of that I rarely experience crashes or problems because of it. Some users find the overwhelming configurability and command-line oriented control to be terrible, but I have used all other major operating systems as daily drivers and most of them have their own issues.
I used to use OS X but since 10.5 their quality control has given way on the desktop as they focus more and more on the mobile segment, plus I'm against the use of Mach as its performance is slower than a BSD-style monolithic kernel or the Amiga kernels on equivalent hardware, and it has become increasingly *unstable* with every subsequent release, requiring more and more hacks to run as I need it.
I also use IRIX for a lot of things because IRIX solved a lot of the problems with the 'UNIX Workstation' problem. While some may argue that the Motif toolkit is ugly, it looks quite similar to OS 3.1 to me, so it is the pot calling the kettle black. The lack of development for IRIX hasn't barred countless ports of various utilities and somewhat updated web browsers, plus XSGI is probably the best iteration of X11 around, with many of the problems that still plague X.Org fixed.
Windows is still used occasionally, mostly Windows 7, but only in cases of absolute need.