When I first started out with shared hosting, I found it difficult to find any comparitive information on the industry standard control panels.

I will add to this when I get a chance but below is a VERY short list of my experiences with some of the most used control panels.

Plesk - Commercial

Home Page: http://www.swsoft.com

I found plesk to be stupidly simple to install, configure and use, however I soon found it to be extremely restrictive when you want to get a bit further under the bonnet and tweak the setup to your specific needs, and what the fuck is up with the partition schema and vhost arrangement?

The main annoyance for me, was the fact that more or less every feature I wanted to add to the build was a commercial extra (with an attached price tag) simple things such as spam assassin & an iptables configuration front-end (which is a requirement for more or less everyone nowadays), I don't really see how they can justify making you pay for open source software when everything else on the market offers you the same for free.

I guess my main hindrance with plesk was the fear of it breaking every 10 minutes if I manually added acls and configuration directives outside of the scope of the control panel, this for me is a major thing as the companies I do work for tend to have very specific requirements.

I also found the company, client & domain management way of thinking a little annoying and surplus to requirements.

Overall not particularly impressed, anyone with minimal linux knowledge would be frustrated when custom implementation is needed.

Webmin - Open Source

Home Page: http://www.webmin.com

Although overall im not really a fan of webmin, I have been known to use it in the past and I can't find an awful lot to complain about with it, it has no rivals for the amount of software modules you can plug into it and the amount of control it gives you over everything, my only bugbear with webmin is the user interface, and the way you navigate around the different areas, to a newbie it is a little confusing to use at first, but that said its very functional, very stable and also free (open source)!

ISPConfig - Open Source

Home Page: http://www.ispconfig.org/

I haven't used ISPConfig a great deal, I have a few gripes with the installer having tried to install it on low-spec VPS systems on my development testbed - Constantly running out of memory!

When I finally did get it working, it was far too much like plesk in terms of client & domain management and that was too much of a turn off for me - also my unfamiliarity with postfix didnt help much, It may well be brilliant and I apologise if I haven't given it enough of a chance but I don't think I'll be recommending it to anyone.

cPanel - Commercial

Home Page: http://www.cpanel.net

My control panel of choice, I haven't used anything that rivals it by a long shot yet, there is also a strong community of good, helpful people both in its staff and end-customers

I've found cPanel to be one of the least restrictive of the control panels I've used, it leaves you plenty of scope to customise your boxes as you need them, without it breaking every 10 minutes.

It does have some faults, but what automated system doesn't? Some of the updates have been a little dubious, and the changelogs are a bit lapse of late, but most of the issues it creates are either easily fixed or are promptly corrected by their staff.

I would recommend cPanel for those with a basic understanding of linux as its far less restrictive than plesk but has the tools and community support to help you out if you get stuck with it.

Configserver also have some great products for it that plug straight in, most free, some not.

Conclusion

So there is my very brief overview of experiences with control panel software, all of which were tested on CentOS boxes, when I get a bit more time, I will add more to this and try and make it a little more structured. That said, hope this helps somebody.