OS/2 i have seen, my grandfather still has a copy in a box, i think the pc it was on is gone though.
MAC is now the new unix and "feels" nice to move around in, very very nice to use. Better hardware specs too on their pc's even though they are higher priced, but i suppose if i wanted a bmw or a ford, i could always say i was overspending.
Windows 7 looks like the first version M$ has gotten really right since 98SE, though its still early to tell, all the reviews from users seem to say it is really what Vista should have been.
Amiga, i'm afraid i dont know, other than the articles online, but it did seem awesome from what i read.
Ubuntu looks pretty cool, but i cant run my school programs on it.
I sometimes dream of a computer like a MAC, that will run anything. Or maybe a web machine where all the programs are run in whatever os box they need.
Used to read a couple years ago that Google was working on that, never found out what happened to it. But that would be nice.
One of these days we will all sit back and say "remember when computers used to run their own os?" and it will all seem like old fashioned, you know?
That would be cool, but well... we will probably have to wait for that, unless some little startup comes along and does it and blows everyone else out of the water...
Like Apple and MS and Amiga did in the beginning.
p.s i wonder what that little startup company name is?