Marketplace. It's horrible, but the area I live in has mostly abandoned craigslist and if you want to buy/sell used stuff, marketplace is where you have to be.
While I do not think that the company needed to modernize the site’s UI, it baffles me that their anti-spam tools are so rudimentary. Most searches yield irrelevant keyword-bombed results, and, such results tend to be nearly identical listings.
I had yearned for a viable Craigslist alternative for years. Sadly, Facebook Marketplace won. I don’t feel comfortable searching for anything due to the fact that Facebook will inevitably use my queries to further profile me.
My guess is that the default state is the scam garbage. It quickly learns your preferences. Which I hate. I miss having my 5 sections of craigslist I could browse over my morning coffee and not feel like I'm missing a deal.