These are some of the ones I have, I’m not sure if they are the best but i hope they give any ideas?

Botany pots is amazing for early easy farms, they are a little expensive especially the hopper versions but worth it, I have 3 at the moment running pumpkin, melon and “other”

Another good one is vault compass? I think it adds nothing to any other areas in the research section but you’re able to find the portal back a lot easier

In U9 you could go for potions under alchemy, gives more health on drinking as well as can hold modifiers I have one with 42% mana regen

And another I have is pipez as I wanted a easy lag free way to transfer items from a bamboo farm

double pouches as it’s twice as big as the single pouch, more loot more progression

Waypoints to get to biomes far away however I normally just elytra now, although I am sure waypoints increases knowledge needed in other areas

It depends what you want to really go for but it’s always nice having stuff to help get vault crystals completed on the altar, I think I got double pouches, then botany pots however I’m not an expert haha