Not sure if this was brought up before (in which case I apologise), but a new thread pops up every hour complaining about AH so it's a bit hard to keep track.
Since there was a conscious decision at some point by the devs to favour Guild Stores over the classic Auction House model, I thought maybe it's worth thinking about something new to introduce to the menu, instead of having to fight over just those two choices.
How about opening a Guild Store for the public?
A guild would need to earn the right to be an open store, like say, by being the most dominant in the Alliance War.
The top dog would be the Global AH and the best of all 3 alliances would be the Local AH for their respective regions (DC, EP, AD). This privilege would be re-evaluated every month, or something like that.
You could play with the listing prices: guild members would have it for free, players in the same region would have one, and players outside the region would pay a slightly higher price. This would fuel a sense of competition to fight for your guild and also for your alliance.
Now, I don't think that the guild should be earning money off the open store, only between their regular members' transactions as per usual. Although this is somewhat backwards, but to keep it fair, their reward should be the fact that they were the best and that they can take pride in their name being known by everyone.
I don't know if you agree, but I think this would introduce a much more compelling game mechanic. Guilds would have additional motivation, people who want to trade globally or locally would have that option to do so, Cyrodiil would get an additional use, bragging rights for members of the winning guilds, etc.