Going by what you can’t live without, then bread if the absolute most important resource. But that’s not even remotely a good metric.
We’re going by what has the most value. That’s crystals for sure. You need them and you can use them to help make you stronger. Crystals are the only currency that you have to “work hard” to get them. You can use them to get everything else in the game (via pro shop + pro chests), but you can’t use anything else to directly buy them, not even real money.
It’s a no brainer really.
Getting back on topic, I do agree that the probability of getting uber items should be converted into getting pro items/tickets.