I’ve done EBay, Craig’s, and letgo. I believe OfferUp is more like family to me. More of a community feeling. Yes all Communities have ups and downs. I’ve had more ups and met more people, good people on OfferUp. I pick OfferUp.
As a seller, I prefer eBay, Carousell, and Mercari.
When buying (local/in-person), I prefer CL by a mile (best boolean search...even better than eBay), but younger folk seem to sell on OfferUp, LetGo,5Miles,etc., especially for "ditching" items, which is why I use OU.