What is the best trait combination if you want to complete all collections in the game?

Loves outdoors for sure, I don’t know about loaner. One of my sims has cheerful, I can’t remember her 3rd quality, I think it might be family oriented. It is taking forever to update my game tonight. Geniuses like keeping their brain active with logic, things like chess…, that might help with rocket building skill and microscope prints. Self assured makes your sims confident a lot….. don’t know if that would help. I think I saw someone mention geek being good for it.

I don't know about regular traits but I would recommend going for the aspiration trait that comes with the collector aspiration. I am talking about the extra trait when selecting an aspiration for a new sim. It can give more collectibles while digging and a higher chance for rare ones.

Hmm...loner might make things difficult with the social aspirations. Having your sim being tense all the time because you have to be out in public to work on an aspiration might be irritating. Or it could be an interesting complication to work around, something to overcome. Depends on how you want to play it :)

A lot of my sims are collectors, and loves the outdoors is definitely helpful, but not necessary. I like adventurous trait because of them getting extra buffs just going to the park, lol. I'm not sure about geek either, it seems like they are the video gamer nuts and to do that you need to be indoors usually. I usually pick for the third trait, something like materialistic, which works good too. Usually I give them the Curator aspiration which motivates them to have the appropriate buffs, like wanting to find another fossil.

That's a lot of collections to complete with just one sim. I don't think traits help that much depending on how you go about completing the collections. Some things you can just buy and some you can gift to your sim that collects stuff or just store collectable items from several sims in a museum. Personally, I prefer to work collections into my gameplay, so different sims for different stuff.

My Collector Sims start with a Nature aspiration like The Curator or Freelance Botanist so they get the bonus Collector trait. The personality traits I use for most of my Young Adults are Music Lover, Genius, and Ambitious. I've used this combination with many Sims, including Vlad, Brant, Caleb, and Salim, who have completed a lot of collections as well as aspirations and careers in various games.

Teens living on their own start with The Curator aspiration. They always start a small garden which unlocks the Freelance Botanist aspiration. Personality traits for teens are Music Lover and Loves Outdoors both of which keep them pretty happy in spite of starting out with nothing, including power if they're living off-the-grid.

@Skyrryx What is the theory behind using Geek or Good for this?