Alquin Academicals :
Would be a bit of a blunt instrument, but why not base the teams *rating on the first 15 players in each squad... this then removes the 10* player exploit and would be most reflective of the team you are looking at.
Would be a plateau at the top though, with so many sides having 205* players from 1 to 15, so no good at sorting out the top teams individually, but across an entire guild it would be pretty reflective.
I quite like the current 'random' anonymity created by the opponent selection for gvg's, primarily because it reduces the possibility of manipulation.
I do like the theory of your suggestion, however allowing guilds to choose opponents would almost certainly introduce some manipulation by unscrupulous guilds and could you imagine the fuss that the conspiracy theorists in the game would kick up!? They'd be twitching and mooning even more than they do already!!!
I get what your saying and yes the conspiracy theorists would have a field day they do now with the current system which as team ranking is taken into account dont ask me how they do it in how match ups are selected its open to maniuplation now with teams not playing ranking games. I do think the starting 15 star rating should be taken into account as well. I just want to get away from just fans deciding the ranking of guilds as i dont think this reflects who the top guilds are any more