ubuntu

Advantages: popular forums provide excellent resources and technical support, fixed version update cycle and technical support, can be upgraded directly from Debian Woody

Advantages: not yet a mature business model

red hat

CentOS

CentOS is the most popular Linux system, but it is the most popular one in the world.

Weaknesses: no mature business model yet

red hat

Benefits: huge number of users, great community support, lots of innovations

Weaknesses: free version (Fedora Core) version lifecycle is too short, poor multimedia support

debain

Strengths: follows GNU specification, 100% free, excellent web and community resources, powerful apt-get

Weaknesses: relatively not easy to install, extremely outdated software in the stable branch

centos

Strengths: very rigorously tested; extremely stable and reliable; free to download and use; five-year long free security updates.

Weaknesses: Lack of the latest Linux technology; the project occasionally fails to deliver on its promise to provide regular security updates and stable releases.

fedora

Strengths: highly innovative; excellent security features; large number of support packages; strict adherence to the free software philosophy; LIVE CD as a carrier, suitable for most mainstream desktop environments.

Weaknesses: Fedora's focus tends to favor enterprise features over desktop utilities; some cutting-edge solutions, such as the premature adoption of KDE 4 and GNOME 3, occasionally overwhelm some desktop users.

suse

Pros: professional, easy-to-use package management system for YaST

Weaknesses: FTP releases are usually 1-3 months behind retail releases

Ubuntu is the best place for newcomers to the world of linux, and is the windows of linux. If you don't know anything about linux, you'd better go with ubuntu. After all, it's easy to give up when you're just starting out with a difficult system

But personally, I'm more optimistic about centos and redhat

There's no reason to be afraid of ubuntu.