HSRP and GLBP both are cisco proprietary protocol.
Hot Standby Router Protocol (HSRP), and Gateway Load Balancing Protocol (GLBP), both allow clients using a default gateway, to have fault tolerance. From the clients perspective, they point to a single default gateway, but behind the scenes, there are between 2 and 4 routers all making sure that the default gateway being used is up and available for those clients. One of the significant differences is that HSRP only performs forwarding on a single router at a time, while GLBP allows load sharing across all the routers in the group, and even proportional sharing if configured that way.
More info on:- http://info.copperriverit.com/CopperRiverITblog/bid/55707/Is-GLBP-better-than-HSRP
HSRP is quite very easy to configure and understandable. GLBP works good but you need to understand how it works then it make much more good than using HSRP.
VSS at the other hand is different than the HSRP or GLBP protocol.
As you migh know HSRP is just provide first-hop redundancy and it is not related to overall throughput of the network.
Converting the core switches to VSS (and having MEC configured in dist/access switches) helps you to improve overall performance as both fabric will be active in VSS and traffic load-balanced. No more STP blocking port in the dist/access switches, while getting chassis-level redundancy.
HTH
Regards
Inayath
