we use comatose, which is not as fully featured out of the box as some of the cms systems you mentioned -
but allows extremely tight integration of your rails webapp with the cms.
Really, as with all things, it depends on your needs -
if the content parts of your site are very separate, then no problem:
use one of the cms systems in your list that you like, perhaps radiant just to keep everything rails-esque.
if commonly a single page will include embedded content you want to manage, and at the same time display a view from your rails app,
then you either need to go with something like comatose which plugins into your rails ap, and let’s you embed content with render calls,
or come up with some other clever way to combine rails views with html from an external site - I don’t know a great way to do that personally, but no doubt it can be done - perhaps using some javascript on the page to display the result of a call to the external cms as html, or using iframes, or a custom helper to pull the content on the serverside and render it - there are ways.
Anyway - that was the thought process that lead me to comatose - of course I have no idea where your needs lie, but there’s my 2 cents anyway.