I'm a HUGE Sims fan! Been playing since Sims 1 in my childhood lol. I go through phases with the game though, where I'll play for 2 months straight, then not touch the game for months. Welcome to the Sims family
My favorite thing to do is Create A Sim! Love figuring out how to make unique looking Sims, and sometimes trying to make them look like people irl, too. I have about 30gbs of custom content though (thank you tumblr), so sometimes I end up just playing in CAS the entire time, without ever actually touching live play lol. I'm awful at building houses, so I usually download those lots the gallery when I need them. I follow a couple of Sims Youtubers that are builders & tend to use their lots. As for favorite challenges... the Not So Berry challenge is alot of fun. So is the Sims 4 Experiences challenge on Tumblr, but that one's great for if you have a bunch of the expansions.