My personal favorite for adding additional traits is
More Traits in CAS. This allows you to add up to 2 additional traits to each sim directly in CAS.
Vicky Sims (chingyu1023) has a
mod that allows you to add additional traits through a menu on your sim. They also have a 100 trait pack, toddler traits, supernatural traits, faithfulness traits and numerous mods that affect your sims' personalities. Truly covers traits so well that I deleted traits from other creators. You can find their Patreon
here.
Kuttoe has a great assortment of traits plus a fun pizza preferences mod. I also recommend Lifetime Quirks for extra personality.
KiaraSims has a lot of great traits as well... often with careers and aspirations to match.
Not really CAS traits, per se, but I also recommend
Give Me Some Talent to adds "traits" that make your sim better or worse at certain skills.
Also recommend checking out the mods from
MissyHissy and Halaene (
Patreon and
Mod the Sims) for making the most of existing traits and preferences, too.
