Hello Bartley
Both HSRP and GLBP are Cisco proprietary protocols while VRRP is an IEEE standard. From my experience, VRRP should only be used when configuring gateway redundancy with other vendors’ equipment. Compared to HSRP and GLBP, it has no load balancing capabilities.
When using Cisco IOS devices, HSRP does not support load balancing while GLBP does, as you correctly state. However, for Nexus devices, HSRP does automatically perform load balancing across multiple gateways. So from a functional standpoint, GLBP should be used with IOS devices, and either HSRP or GLBP should be used with Nexus devices.
Now why is HSRP more popular? Probably because it was introduced first, and everyone knows it, and may not want to learn the newer protocol. It also seams that until recently, Cisco has include HSRP in its certifications much more than GLBP, but I’m not sure why. I don’t think there’s a legitimate design reason however.
I hope this has been helpful!
Laz