You should have all three, at least the ones that pertain to you. The ORCID, while relatively new, is independent of any particular publisher or database. Because it can be associated with any scholarly output (not just papers in a particular group of journals), ORCID has arguably become the most important. The ResearcherID is for Thomson Reuters authors, while Scopus Author ID is for items indexed in Scopus, but both organizations work with ORCID. If you publish with Thomson Reuters or are indexed in Scopus, you are encouraged to link your IDs there with an ORCID.

You should have all three, at least the ones that pertain to you. The ORCID, while relatively new, is independent of any particular publisher or database. Because it can be associated with any scholarly output (not just papers in a particular group of journals), ORCID has arguably become the most important. The ResearcherID is for Thomson Reuters authors, while Scopus Author ID is for items indexed in Scopus, but both organizations work with ORCID. If you publish with Thomson Reuters or are indexed in Scopus, you are encouraged to link your IDs there with an ORCID.

I agree with Witwer. This is an area where no universally recognized standard register has been accepted yet.

@Jose, we are still far away from a single unified system! Maybe the development of such system is in progress, but, as my predecessors have noted, we are going to use many of ID's ! It would be nice if unique standard for those purpose was adopted.

But in practice, Which of these four systems have been given you some benefit of visibility?

For example, I consider that ResearchGate offers more visibility.

ORCID can provide a better description of bibliographic data, especially when items are transferred from SCOPUS. But duplication of information is generated if the data is transferred from the two databases: SCOPUS ID and ResearchID.

ResearchID seems better organized and offers information about citation metrics included the H Index.

Google Scholar & Cited Get more information that provides visibility appointments.

@Jose, I do agree on ResearchGate visibility, comparing to other systems!

I reckon you might have to (painstakingly) make sure you're up to date with several, not just one. Currently, every so often, I check through researchgate, ORCID (v useful to have, as many diff types of journals ask for your ORCID ID), google scholar, and my university's own internal system (Sympletic elements) just to make sure it all adds up. Oh yeah, then I would add all (or if you have many, maybe just your "top 5") publications to my LinkedIn profile as well. Either way it's a lot of hassle (see link talking about pros- and many cons- of diff websites for this). Good luck!

http://nlphist.hypotheses.org/107

ORCID is going to the game changer in this. They are not for profit and works with all information providers. There are issues to be cleared along the way of course but they are already working with a number of major and small publishers who request the authors of manuscripts to have an ORCID ID. These can then be captured in the metadata and be indexed accordingly. That's just one area though.

They are also working with university libraries, funding agencies etc to have the same requirement.

Dear @Friends, ORCID has announced today some changes and new features.

New: The ORCID Inbox

To help you manage how and when you receive notifications from ORCID, we have developed an ORCID Inbox system, orcid.org/inbox. You can choose which messages are delivered to your Inbox and how frequently you receive alerts. For more information and to reset the default weekly alert frequency, please see "About the ORCID Inbox"

New: Permission requests for ORCID record auto-updates ...

http://support.orcid.org/knowledgebase/articles/665437

Please see https://researchid.co that is unified system to maintain Research Profile