I'm not a CMS expert, but this issue has been brought up many times here.
There're more then 200 threads dealing with CMS questions in this forum alone. I've gathered some of the most accurate and most recent ones (since 2004) in the following list:

But first, some useful sites:


Hotscripts.com - News Publishing Scripts (http://www.hotscripts.com/PHP/Scripts_and_Programs/News_Publishing/index.html)
Hotscripts.com - CMS (http://www.hotscripts.com/PHP/Scripts_and_Programs/Content_Management/index.html)
Hotscripts.com - Portal Systems (http://www.hotscripts.com/PHP/Scripts_and_Programs/Portal_Systems/index.html)
OpenSourceCMS - Try Before you Install (http://www.opensourcecms.com)
CMS Matrix - The Content Management Comparison Tool (http://www.cmsmatrix.org)


And then WHT's own threads about CMSs:

Looking for an easy CMS program (http://webhostingtalk.com/showthread.php?t=479870)

Easy CMS (http://webhostingtalk.com/showthread.php?t=483948)

CMS requirements! (http://webhostingtalk.com/showthread.php?t=483993)

CMS or pro webdesign company? (http://webhostingtalk.com/showthread.php?t=480010)

Which CMS should I get? (http://webhostingtalk.com/showthread.php?t=481919)

Need a CMS (http://webhostingtalk.com/showthread.php?t=480439)

Looking for a reviews/cms script (http://webhostingtalk.com/showthread.php?t=481672)

opensourcecms.com is a great site (http://webhostingtalk.com/showthread.php?t=478268)

Which cms for me? (http://webhostingtalk.com/showthread.php?t=479242)

Suggestion for best CMS for a town's chamber of commerce? (http://webhostingtalk.com/showthread.php?t=478428)

CMS help! (http://webhostingtalk.com/showthread.php?t=473974)

CMS? Which would you suggest? (http://webhostingtalk.com/showthread.php?t=470781)

Portal software opinions: Xoops vs Mambo vs Drupal (http://webhostingtalk.com/showthread.php?t=465995)

Which CMS? (http://webhostingtalk.com/showthread.php?t=471836)

Newbie Needs Help With CMS Choice (http://webhostingtalk.com/showthread.php?t=472984)

Looking for a specific type of content management system (http://webhostingtalk.com/showthread.php?t=472750)

Content management systems (http://webhostingtalk.com/showthread.php?t=469111)

Searching for CMS for clanwebsites (http://webhostingtalk.com/showthread.php?t=468557)

a CMS with forum and SEo thing.. Urgent advice needed (http://webhostingtalk.com/showthread.php?t=467994)

Basic, Intergrated CMS (http://webhostingtalk.com/showthread.php?t=463249)

Cms (http://webhostingtalk.com/showthread.php?t=452646)

Which CMS do you use and why? (http://webhostingtalk.com/showthread.php?t=454383)

Which content management is the best? (http://webhostingtalk.com/showthread.php?t=449917)

Opensource CMS backend for custom designs (http://webhostingtalk.com/showthread.php?t=445936)

Recommend a CMS (http://webhostingtalk.com/showthread.php?t=442233)

Poll: Which CMS? (http://webhostingtalk.com/showthread.php?t=436512)

What is the best cms? (http://webhostingtalk.com/showthread.php?t=436910)

Recommend A Good CMS (http://webhostingtalk.com/showthread.php?t=441398)

A good, safe and reliable CMS (http://webhostingtalk.com/showthread.php?t=434500)

CMS - who has any prior experience? (http://webhostingtalk.com/showthread.php?t=430739)

Best cms for a hardware review site? (http://webhostingtalk.com/showthread.php?t=431327)

Hey Guys, Cms Needed (http://webhostingtalk.com/showthread.php?t=430155)

CMS or easy way to update a site? (http://webhostingtalk.com/showthread.php?t=428763)

Know of a free CMS script? (http://webhostingtalk.com/showthread.php?t=427564)

What CMS should I choose? (http://webhostingtalk.com/showthread.php?t=417535)

Advice for 800 online users cms (http://webhostingtalk.com/showthread.php?t=416049)

CMS with HTML extension (http://webhostingtalk.com/showthread.php?t=415986)

Your favourite CMS software? (http://webhostingtalk.com/showthread.php?t=413635)

Content Management Recommendations? (http://webhostingtalk.com/showthread.php?t=400597)

Best CMS for... (http://webhostingtalk.com/showthread.php?t=395553)

Looking for a CMS (http://webhostingtalk.com/showthread.php?t=348720)

Content Management Solution (CMS) (http://webhostingtalk.com/showthread.php?t=399770)

Good CMS (http://webhostingtalk.com/showthread.php?t=390265)

Best CMS compatible with google indexing. (http://webhostingtalk.com/showthread.php?t=391148)

Which CMS? (http://webhostingtalk.com/showthread.php?t=379735)

Whats a good CMS to use? (http://webhostingtalk.com/showthread.php?t=382267)

Content Management System (http://webhostingtalk.com/showthread.php?t=379260)

CMS / Forum software package Recommendation, anyone? (http://webhostingtalk.com/showthread.php?t=359802)

Website Update Script (http://webhostingtalk.com/showthread.php?t=375334)

Content manager system (http://webhostingtalk.com/showthread.php?t=365920)

Best portal Management script? (http://webhostingtalk.com/showthread.php?t=353052)

Trouble choosing a CMS (Content Management System) (http://webhostingtalk.com/showthread.php?t=341262)

Content Management Systems. . . (http://webhostingtalk.com/showthread.php?t=329806)

Thanks for putting them all in one thread! Seems to be easier this way :)