I have to be honest out of the three, only two are really in the running, I tried AmigaWriter and it was by far the most horrid WP experience I ever came across.
Day to day I used WordWorth and it really was a dream to use, with a clean, modern (well, modern for the time) interface that really did leave you alone to get on with what you needed to do, I must have logged thousands of hours with WordWorth over the years.
That said, there were jobs that I think FinalWriter simply did better, it felt to me less of a pure word processor such as WordWorth and more like a step toward desktop publishing (but not as extreme as PageStream). I personaly didn't much care for the interface but I did use it and it was as stable as a rock.
But yeah, AmigaWriter... Crap interface, poorly thought out, unstable, few options, no ability (at the time I tried it, it may have changed since) to save to RTF or similar portable format... Just really, terribly poor.
These days... I tend to use OpenOffice Writer, though I'll use Abiword at a pinch.
My back to school pack A500 came with Pro Write, it was with that piece of software I wrote my first short story...
Over 15 years ago now.