A useful question, and I hope you will get more replies from people who have used more than one.
I have used Final Writer a little many years ago, installed and looked at, but not really used Wordworth, and have not installed or used Amiga Writer 2.2 yet.
I think Final Writer is a fairly capable and easy to use and understand word processor, but like you, I would be interested in reading other reviews and opinions.
On the PC I have switched to Open Office and refuse to buy another copy of Microsoft Office ever again.
I hate Word and actually prefer WordPerfect over any other word processor I have ever used so far.