What I really liked in AmigaOS is:
-It is small. It does not make sense with today´s machines, but compare Windows Vista and Windows98 running on a modern PC, and Win98 will perform better, because it is lighter. We don´t need a mammoth
-It is simple. There are no hidden and difficult to find and edit configuration files like Win and Linux.
-It boots fast. My 14MHz A1200 takes around 15 seconds to boot, My Win98 Takes around 40 seconds and my XP PC at work takes and awesome 6 minutes! I fell like loading ZX Spectrum software from tape, and see no excuses to take that long in "modern" OS's I´ve never measured my Ubuntu, but it´s not that fast also.
-You can do most of the stuff from WB. Rarely I had to go to CLI for ordinary stuff, unlike Linux. It is time to leave the command typing on the past, and use it only for development
-Software installation is simple. I´m against installers, the best isntallation for me is a directory copy. The Amiga Installer is really simple also.
-Multitasking works, unlike Windows. Yes, it could be VERY improved (memory protection and all that stuff everybody knows...), but it seems to work way better than Win (no better than Linux)
-Screens! With the drag down feature! That was really useful. Even AROS still doesn´t support it
-Big bitmap screens. Quite useful rather than multiple desktops like MacOS and some *nix. Just move the mouse and you find more space...
-Big Icons. They look cool
-Datatypes
-Easy directory structure. C, S, Devs, etc... Everything in a simple to find place
-Autoconfig. But PCI is good enough for me, and I know that this relies on hardware
-Memory gauge at WB´s bar. A free hard drive space one would be useful also
Now, if AROS have these features, I will be really happy, be it 3.1 compatible or not.
Probably all the fanatics will start shooting me with Linux this, Windows that, Mac this. This is my personal opinion, and is what I expect from "modern" OSs and can´t have at all, but had at the outdated 3.1