What do you think is the best OS? The most user friendly, I think, would be Windows 7.
For advanced users, I'd probably go for Ubuntu or Linux Mint(then again; Mint is fairly easy to adapt to, and Ubuntu is just painfully slow on some computers; but it has alot of great software.)
I always preferred Windows. I just like how it looks and works. I've used mac before and it's kinda meh. Never trued anything else and probably never will.
For a user experience it will be Windows 8 for me. I also owned a mac for some time and was not to pleased with it. Both macs and windows have their pros though so i can't complain. I did like the mac for programming that was such an ease of use.