As mentioned it all depends on what you’re looking for and what you focus on doing in the game.
Crafted Potions - color codes your 1, 2, and 3 trait potions that you have crafted with green, blue, and purple, while looted potion are white so you can easily tell them apart in your inventory
Mobil Bank - allows you to check what you have in your bank (not deposit or withdraw) from anywhere, you can also check what your other characters have on them without the tedious process of logging in and out.
Harven’s potions alert - I especially like how it tells me when the cooldown is over so I can take a potion again so I’m not needlesly hitting Q too soon, I also appreciate the ability to set it to auto-select a particular potion depending on a particular stat being low, this makes using potions much easier and really ought to be part of the base game. Before finding this addon I almost never used potions, or only used one type, because I found the selection process too clunky in the midst of battle.
OmNomNom! - Write your own notification that will be displayed when your food or drink runs out - this is helpful if it expires in the middle of a dungeon and you may not have noticed.