This has been something debated, long before AH was even around. Was definitely something people kept talking about in AW as well.
But here's my theory on it, for what it is worth.
Three sides is the way to go. The problem is with the maps. Now I'm not here to rag on the maps suck or anything like that. But if you look at the maps, each side of the map is different, but its the same "hot spots" that produce the GV fights, or furballs, which is what majority of the people are looking for. In AW, every side of the map was proportionate to the other. So the same fights could be found, no matter what side you were on. Although it would become an "eye-sore", this seems to be the best way to get all 3 sides to fight on the same scale. And this doesn't always work either.
This is the same reason why people complain about the maps. People are accustomed to certain fights with certain maps, and when the fights are taken away, all of a sudden "this map sucks."
Now I don't know if this has been tested, and if it hasn't, could it be? People who makes maps, take this into consideration next time you make the maps.