What to upgrade next?

[Chawsky]

I have:
6 - 11 cannons
3 - 10 archer towers
4 - 9 archer towers
4 - 7 Wiz Towers
4 - 6 Air Defense
4 - 7 Mortars
4 - 4 teslas
1 - 3 xbow
2 - 2 xbow
2 - inferno towers

All walls are LVL 8+ and heroes are lvl 6+
I'm looking to keep some builders busy on defense. What do ya think?

[Shintenshi]

Please powerup your Teslas; they are so so useful.