As always with these type of threads, my vote still goes to AROS.
I know there are a bunch (small bunch) of people who use their A1s with the OS4 pre-release and Peg users out there who are quite happy. I also know that there are a lot of people who are happy playing with their classics too, but for whom (either by availability, cost, etc...) neither of those solutions is viable. This leaves AROS.
Some people are probably like me, got stuck in Windows land for a while before moving to a Mac or Linux, or just went straight to Linux after their Amiga time and are happy there. I wasn't happy with Windows and I wasn't / still am not happy with Linux. Even my Mac as much as I think it kicks ass, still leaves me wanting an Amiga like system. They all work but there is something missing to the overall design and feel of the system. Simplicity perhaps? Elegance (or what I perceive as a more elegant solution...) This is where I think AROS has the most potential - former users or people who are looking for something lighter, faster, and tighter in general than Linux. My install of FedoraCore 4 on my PC runs well enough, but I admit it gets less use than UAE on my Mac. Why? There just isn't that much compelling for me to do in Linux. Everything I can do there I can do faster and easier on the Mac...I still enjoy tinkering with Linux but there are times when I just turn away from it and leave it off for a couple weeks when something ticks me off or I get sick of having to deal with the bloat and dependancies to install anything that wasn't targeted specifically to my kernel/desktop/blah blah blah with a package. On the flip side, my Mac doesn't offer me the freedom to tinker as much as I like to but has been rock solid for me.
I watch AROS daily for changes, news, new apps. I come to Amiga.org daily to see if there is any news on the OS4 / Morph fronts. Of any of them, I think AROS has the most news to report throughout the year. I got sick of hoping, praying, begging for something to be done right with Amiga since Commodore as I know most everybody else has.
The reasons for AROS existing are the same for any other alternative OS...there are people out there who know things could be done better/simpler/faster/challeng of doing it... take your pick. Same goes for SkyOS, ReactOS (Do windows better than windows?),etc... Progress may be slow, but I think its moving faster than the alternative "Amiga" choices.
GO AROS GO!
