Harking back to the days of the War Island minigame, the best map was the four player one. The three player maps were more often than not resolved by two players beating up on the third, and when that was not the case, when there was a more or less even three-way standoff happening, each player would hunker down and the game would drag on interminably. That seems to be the state of affairs in any three way game. It's the strategically optimal way to play.
So in the future I think it would be better to have a four realm island, with one realm being at Toren Stronghold. Even though it's not the ideal place for a fourth realm to be, it would still improve the strategic dynamic.