When was AmigaOS the number one OS. I must have missed that nano-second 
Probably depends what you are rating it on. People seem to automatically think #1 of something should be based on sales. When we all know the most popular thing is not the best thing and the best thing is not the best selling. I'm sure we can all list some technologies that were better, but lost out to lesser technology because of marketing.
I would definitely say for a while, Amiga was the #1 choice computer for personal use, for graphics use, for gaming, and for video editing.
