We use not CMS, as I personally somewhat have a dislike against these. NGEmu is built together out of self written scripts (for example the articles section, the news script, the compatibility list) and modified pre-made scripts (for example download script, links section).
I'm currently working on replacing all of them with custom ones, I might even publish our CMS system then, as it's especially useful for emulation sites, coming with everything you might need already pre-made. But we'll have to see about that, gotta finish it first now (today comes the news script, needs an edit function badly )
Post-nuke and others like it can be great if users didn't always just stick to the default stuff. I personally am extremely familiar with the code of Post-Nuke and have done wonders with it and have made tons of personal scripts for it that work great. I just finished convertng over www.emulation64.com not to long ago and I run www.psxfanatics.com that also uses post-nuke. It just depends on how much knowledge and effort you to put towards it that will make the difference.
I totally agree with Wormie on this, PHP/Post-Nuke are an excellent way to run a site as long as you're willing to modify the code to suit your needs, unfortunately there are literally hundreds of sites that use the default settings and look which is retarded, and it labels every other nuke site as being a template based crap site not worth checking. However, those who do take the time to modify the code to suit their needs can create very professional looking sites that creatively handle the information and aren't obviously a nuke site at first glance And btw, I admin EmuHelp
PHP/PostNuke can be nice indeed, but ofcourse the customizing/adding your own scripts takes lots of time and effort; if your site needs a lot of features PHP/PostNuke/any CMS doesn't offer, <b>and</b> you have the knowledge and time to make your own CMS (in NGEmu's case, that's "Bobbi & friends"; don't count me in though ), you'll understand the latter is preferred.
I think that may be the problem with standard CMS's: they're mostly used by people who don't want to put too much time in it. There aren't many people who do, probably cause the pros (not saying you aren't one of 'em Wormie ) often prefer to make their own CMS as long as they have enough time. And as passive said, it's the cheap PHP/PostNuke sites which make the better PHP/PostNuke sites out there look like "not worth checking"...