Well, you could try and use Boardman21s example & how he rates different builds…
Mostly tho, I figure there are three ways to rate a build - one based on completing all empowered level 100 Monoliths (and obviously the campaign), one based on Arena pushing & one based on Empowered Monolith Endgame… How far you can push a build in Arena based on number of waves (see the Ladder) and how far you can get in MoF based on Corruption level (.e.g. level 300 for specific unique drop farming etc)…