I have sampled all 3.
I tried Amiga Writer only breifly, it slowed my 030 and appeared lacking in features. It's no longer on the HD.
Still have WordWorth 4SE (from a bundle, I think) installed on the HD. It starts to run but quits, 060 problem maybe. It looked nice years ago, but, I never had a good reason to switch to it.
I started with Final Copy II. Back in the day, it's printed output was the best on printers available then. It ran well on 68000 at 7Mhz. It had an intuitive menu system and all the basic word processing functionality you could want. It had some simple graphic drawing abilities. I still use it on lower spec'ed Amigas. It will run on retargetable screens.
Upgraded to Final Writer 5. It had a more colorful interface, more graphic abilities (some found in DTP apps), but taxed a 7Mhz machine. Works well with a graphics card (probably AGA, too) and an 020 or better. I still use this the most.
Final Writer 97 added more exotic features to out-do WW. These got in my way. For Example, clicking down a page in a blank area would start a new section-article-chapter-something. Final Writer 97 would treat this as a seperate object from the original body of work. This is probably great for some power users, but it always cost me extra time trying to undo something I did by accident.
I haven't used them in a long time, but, I think Final Writer (maybe Final Copy, too) could import and export a number of industry text formats.
OT: I bought Word Perfect with my first A500 in 1989. It was already no longer supported and I felt it operated like a ported program. I always liked the apps written to run natively on the Amiga much better.