What to spend gems on?

So i got an itunes giftcard for christmas but wondered... should i buy the remaining builders (3 of them) or just gem all the buildings i can?
Thanks

visibly

100% get the 3 builders first.

Builders! Then keep the rest of the gems for boost events like this one now.

Builders, then boosts. Especially boosting DE drill, i think that ones extra nice.