I know this is probably going to start a huge "this is the best OS," "No, this is!" "Flame" "Flame" war, but please try not to do this.
Anyway, What are the best OS's in your opinions? Please give reasons for each, and what you would suggest for different users or uses(Ex: Newbies, Programmers, [I know someone's going to flame for this] Hackers, Networking, etc.).
Thanks for your input, and again, please, no wars of any type on this, please.