What lab upgrade should I buy?

I have been farming elixer and I now have 3 million. What should I upgrade in the lab?

i have

Lvl 5 barbs
lvl 5 archer
lvl 4 gobs
lvl 5 giant
lvl 4 wallbreaker
lvl 3 balloon
lvl 4 wiz
lvl 3 healer
lvl 1 dragon
lvl 4 lightning
lvl 3 heal
lvl 4 rage

i also could upgrade a building. Check out my base:
Clan: REVANJONO
IGN: Rick-Ono

What level is your lab?

What troops have you not upgraded yet?

Wizards to 5 since they get a huge dps increase, then balloons because they're awesome and yours are level 3, followed by drags since mass drag is pretty effective.

Wizards, Goblins, and Wallbreakers. In no particular order.

The idea of lab upgrade order is to max out the troops you use the most, and then max the rest.

Cheers,
B.

Thanks all. I think I'll go with wizards.

Dragon if you're using it in CW. If not, Wizard.

Wizards and Balloons ;)