Thanks for your response. I agree that NSX is more of a closed system, and may not have good support for Hyper-V as well.
One thing which i found favorable in NSX is that the configuration is easier. The VXLAN-VLAN bindings are configured through the NSX controller and also the L3 routes for communicating with the physical network. And this information is sent to the switches over the OVSDB schema. With EVPN, all the bindings and the customer information must be plumbed manually on the switches and this can be cubmersome for large deployments.
On the other hand, BGP is a more robust protocol and the chances of interoperability are much higher in the future. Moreover, there is no dependancy on a controller.