Essential Equipment to Hunt

[Spire]

As far as I know there really isn't a guide for newer players (and old ones who have completely forgotten how to play) on what equipment/cards they should be trying to obtain.

So my question is, what cards/equipment are recommended for players to try and get a hold of, regardless of time investment? (excluding .03% mvp drops) (Example: +7 armor, raydric card, pasana armor, etc.)

I'm asking this because I would like to join up in parties, and would like to finish up a set of armor for my characters to swap around in order to be helpful and not a burden on other members.