Luckily it's not winner takes all, nor is it "second place is the first loser".
SUSE may be overlooked from a US perspective, which is why they get much less coverage than they deserve on sites like HN. They are huge in Europe and employ some exceptionally good people, and have been making probably the most solid distro out there since ~1994.
Oh I totally agree with you. Suse Linux 6.0 was my very first linux distribution around 1998 or 1999. I've professionally managed SLES, SLED, and even migrated a netware server to open enterprise server. It is great stuff and I'm glad to see it still alive.
The market is big enough for multiple large Linux distributions (Redhat, SUSE, and Debian^WUbuntu*). The market continues to grow as more things transition to computers.
Scientific Linux, which was built exclusively for HPC, was based on CentOS.