If Amiga never existed, I would use an Apple iBook. I love OS X. I sold my last Mac a little while ago but now I miss it and want to buy another.
I had 3 SGI Indigo 2's given to me by a friend at work, and I played with them for about a week, but found Irix very slow (compared to Amiga OS) so I ended up putting them on Ebay.