[fChk]

What is your preferred OS, which is the one you use of the majority of your machines, and why?

Any RedHat-based Linux distribution should do the trick for me. By RedHat-based, I mean any distribution that uses RedHat's RPM package manager should be just fine; this includes Arch Linux, Mandriva Linux etc....

Of course, why go to the forks if the original is still around ?.. This is why I did stick with RedHat's own ecosystem since the start; RHEL, CentOS and Fedora, which are the same thing/product really, packaged to meet specific needs.

Now to pick up one as the 'preferred OS' I would go with Fedora without any hesitation. It's powerful, highly customizable ,  cutting-edge and ... FREE!.. One upgrade every 6 months and 2 kernel upgrades a week!..

Besides, I'm fond of the way CentOS enforces it's directory permissions (stricter than others).

Not sure what you meant here ?..

People say that Ubuntu is more suitable for Linux newbies, but honestly I started with CentOS and still here. I like Debian though, compared to Ubuntu. 

Not really!.. Any distribution is suitable for any Linux newbie. What Ubuntu was created for is to attract 'Lazy Windows Users' who are willing to switch to Linux provided that there is a distribution that mimick a lot of Windows semantics(/UI). AND that's just what Ubuntu did from its early days to today -of course to the dismay of the purist among the Linux community.

Canonical (the enterprise behind Ubuntu) borrowed a lot from Microsoft's M.O. and that did show into its flagship product: Ubuntu; it smells like a Windows all over the place :-)

Package manager being a bit dated on CentOS is definitely a concern, but with a couple years of experience in Linux now I find it better to alt compile whatever I need rather than switching OS. 

I think you're referring to 'yum' here. if so, you may need to know that you can also install the newer 'dnf' package manager in CentOS-7 too. It's there but not installed by default.

Thus just install it and you can still use both.