Speaking "business", you can trace down most used Linux distris in the field two two "roots" (or "root philosophies"): Debian and RedHat. So if you learn these two, you won't feel alien on any distribution used in business context. Depending on the business performed, companies tend to the one or other – usually for reasons of support and contracts (e.g. the Oracle RDBMS is mainly supported on RedHat and SLES, but not on Debian).
For easy starters, both camps have "derivates" with bigger communities, so you can expect help with your questions. The most famous in the Debian camp certainly is Ubuntu (which also has its own SE site, AskUbuntu), which again has several flavours and derivates (I personally prefer Linux Mint on my desktop machines, which is very user friendly, while using "plain Debian" on my servers). In the RedHat camp that would be CentOS (which you already know) or OpenSuSE (as community counterpart for SuSE Enterprise Linux aka SLES).
Help on "all things Linux" which are not specifically Ubuntu also has its home on SE, with our sister site "Unix & Linux" – so you're well covered with any choice you make from the above.
As I already told you: for specific recommendations we would need much more specific requirements mentioned in your post: what you want to run on it (see the "Oracle example"), what your level of experience is, etc.