I experimented with a few. The last one was Joomla which, I have to admit is very powerfull.
Too much probably for my needs.
Then I discovered CMS made Simple and this is exactly what I was looking for. Clean and Simple.

I really like the modular template approach and the system of tags.
I am still working on the template (derived from the default 1 column template) but I am already quite happy with the current result.
My site here: http://www.chauveau-central.net/cms/
All comments are welcome especially if you see some problems with IE (I am on linux with Firefox).
It took me 3 evenings to reach that point and here are the notes I took during that time.
This is a mix of ideas, feature requests, questions and usability problems.
[1] How to create a menu containing only "link" pages without their parent?
Fot example, I have a Member page in which I want to provide links to
different servers. The links are children of the "member" page:
8 Members
8.1 Login
8.2 WebMail
In a page, I want to provide the links but without the 'Member' title.
I currently do
{ menu start_element="8.1" show_root_siblings="1" }
I do not like using 8.1 since the position 8 of the Member page is likely to change. I cannot use start_name either since the link pages do not have a name.
Anyways, the show_root_siblings method seems a bit upside down to me.
An option to only display the children seems more logical (e.g. show_start="false")\
[2] The pages to edit templates & stylesheets should also have some Preview/Submit/Apply/Cancel buttons on top.
[3] The templates, stylesheets ... are provided in large table in which the name of the object is in the top left column.
When editing my template I found very inconvenient to have to move the mouse to the other side of the row, for example to access the CSS button (especially when using the touchpad on my laptop).
Even with the coloring, Iit is very easy to keep track of the 'line' and to select the wrong one.
I propose to move the 'Template' column to the middle of the table and all the 'action buttons' to the left.
The 'delete' button could stay on the far right since it is potentially dangerous.
For example, the new order could be:
SelectBox / CSS / Copy / Edit / Template / Default / Active / SetAllPage/Delete
[4] The title of the login page (/admin/login.php) is "CMS Login".
It would be nice if the site name was indicated there (especially for bookmarking).
[5] The start/stopExpandCollapse tag is nice but it always scrolls the page to the beggining the the expanded area.
This is pretty annoying.
[6] The prev & next relationnal links (e.g. {cms_selflink dir="prev"} ) always refer to the previous or next page even if that page is at totally different level.
For example in my site, the 'prev' page of the page "4 - Macro Photography" is currently "3.4.8 - Where to I get Help?".
That is pretty confusing so I would rather limit the navigation to the previous and next sibblings.
Is there a way to do that with the current version?
[7] Is there a "powered by CMSMS" button anywhere?
[8] The {menu} could have an option to use the 'Title' of the pages instead of their 'Menu Text'.
The way I see it is that the main purpose of 'Menu Text' is to provide a short version of 'Title' that fits in a menu with a fixed width. A menu inserted into a page (e.g. as a normal bulleted list) does not have such size constraint so the 'Title' might be more suitable.
[9] I really do not like editing my pages & templates using the browser.
Is there a way to inline a local file in a page content?
A bit like the {embed} tag but without using a iframe and the cmsms tags should be interpreted.
Ideally, that would be something likeas simple as {inline file="../foo.txt"}
The funny thing is that I just discovered the Smarty documentation and a tag really exists with that syntax

So I could remove that item but it serves as an example for [11] below.
[10] A variant of {edit} that opens in another window would be nice.
[11] The term Smarty appears a few times in the documentation without being really explained.
It took me 4 days to figure out what Smarty really is

some of the tags explained in the Smarty documentation are really usefull: for example {inline} and {fetch}
So Smarty should be clearly introduced in the FAQ or in the User Manual.