Honest I'm torn. The Hermit Confidant has been my favorite so far in 5, in 3 it was Justice (relatively similar stories for both). But when it comes to actual battles I don't really have a go-to arcana of choice. I try to get as much of a mix in as possible, so anything that has a good combination of physical and magic attacks is always the way I go, which oftentimes involves a bit of legwork on my end in the velvet room.
My favorite arcana would have to be the magician arcana. The most recent persona game I have played is p4g. In it, most of my personas were of the magician arcana, and they helped a lot. And also, poor yosuke. sorry about saki-senpai... 😢
Mhm... The Fool (not just bc its the protagonist's arcana) but because its the one whos filled with more possibilities. the number represents everything and also nothing, and sometimes it can't be expressed as a number which is quite mysterious and fascinating. also, the fool represents a journey and the knowledge gained during this journey. it means impulsiveness, creativity and also recklessness.