We have some ESXi servers v6.5 U3 Build 19997716 and some ESXi servers v6.5 Build 4564106 (that we're going to update them). What is the recommended version of VCSA to install?
Any of vCenter 6.7. Better the latest.
Have you used vCenter before? Be ready that you will have only 60 days trial version. Than license will be needed for vCenter and for ESXi hosts.