Who to E6?

Hi, I've been playing HSR since the start of this year and I've only ever pulled a few times for limited 5 star characters and I'm close to having enough jades for an E6S1.

Just wanted to see some general opinions on who to E6. I'm not asking for a specific character, I'm asking for more of an overall idea who which types of character to E6. For example, maybe supports/dps...or maybe someone with a specific type of kit. What do you all think?

P.S: please don't say stuff like get multiple units.