Bill Kutik’s regular handicapping of the ‘big 3’ SaaS vendors is an interesting read. The most recent entry can be found here.
Bill goes through each of SAP/SuccessFactors, Oracle and Workday in turn and gives an update on customer numbers however, I think it’s easier to view in a graph:
Here we can see that SuccessFactors has 1,250 HCM customers (on Employee Central) and 1,900 on their Financials solution (S/4 HANA ERP).
Oracle is slightly ahead with HCM Cloud Core HR customer numbers, and far ahead with ERP Cloud.
Workday is another 50 customers ahead with their HCM offering, but at a fraction of the customer count on the Financials side.
Also worth noting is that Oracle’s figures are from May 2016, SAP’s from Jun 16 and Workday’s from Sept 16, so this direct comparison is probably unfair to SAP and particularly Oracle as they are likely to have gained new customers in the interim.