Just to add complexity, the next question is when do you need a tower by?
In deck's that are fueled by towers, or require early towers, then that's great, but Instosis, is fueled by Super Novas. You don't need a single tower in the deck to pull off the attack. The towers only fuel the fast draw. The question for a deck like instosis does not stop at where is my tower? It only cares that you get a couple towers by AND an electrum hour glass by a certain turn for efficiency. You also care about when can you start stalling/pulling extra cards.
I've done a bunch of the calculations, I choose the upped sundials, because of the higher rate of getting the sundial chain at the right time.
