Ok, since everyone is suggesting, so will I.
Things to know:
Red lane: Creep path
Blue and green circles: Towers
Blue and green square: Bases
Orange circle: Tower indestructible till other destructible towers of its lane are destroyed.
Since center has 3 and other have 4 towers, maybe central one should be little bit stronger.
Also if a tower of 1 line gets destroyed, maybe some creeps from it get diverted to other one, making tower killing a gamble.
Lover left is supposed to be on some mountain like suggested by Xarwin (I think) few posts ago.
Upper right has 2 lanes with only 1 side having a tower. I thought that maybe side that doesn't have the tower has more creeps coming that way. And when tower is killed some creeps are redirected to other lane, and only left same amount as opposing side which had the tower. That will then put pressure on team that lost the tower to kill other one faster, especially since that side will have more creeps coming now and having an advantage of a tower. Also path that creeps have to take will have to me same to balance it cuz there are towers missing.
I hope you understood anything. If not, I will explain again

NOTE: Paths can be zigzagged more and wobbled, this is just a really rough sketch.