Quick update: I contacted Nimble Support and they have confirmed that using the Windows adapter is best for Windows, and VMware for ESX. Nimble Support have also checked this with Cisco.
They added the following link from Cisco:
Operating System Specific Adapter Policies
By default, Cisco UCS provides a set of Ethernet adapter policies and Fibre Channel adapter policies. These policies include the recommended settings for each supported server operating system. Operating systems are sensitive to the settings in these policies. Storage vendors typically require non-default adapter settings. You can find the details of these required settings on the support list provided by those vendors.
We recommend that you use the values in these policies for the applicable operating system. Do not modify any of the values in the default policies unless directed to do so by Cisco Technical Support.