My playstyle is free will off and they mucked that up in this game, therefore I need at least Self configureable autonomy (now part of MCCC) and SelectablePets to prevent sims from wrestling control from me, especially in large households.
Everything else is just nice to have, like children being able to play pingpong, or all the vehicles moddlers have made from the basic bicycle (motorbike, wheelchair, ATV, horse, I even have a rideable Kelpie on base of the aqua zipper, it's amazing). Things like "choose your helmet" help individualize sims, "Show buff gained from soak baths right there in the pie menu" is helpful, "Spar for everyone" is great for storytelling, then there are some cheaty mods like "Power Nap" (but I have full control over how cheaty they are in practise because I can just opt not to use the option)... basically mods turn an already enjoyable game into one that I want to continue to play for years.
My most important occult is android, a human looking servo. Since mods are always in danger of getting discontinued, I create my androids with cheated satisfaction points to buy reward traits like no hunger, no sleep and antiseptic. So that's something I do not trust mods with.