Where do YOU sell your old phones? Recommendations & Warnings!

I'm looking to sell my old phone soon and wanted to tap into the collective wisdom of this forum.

So, my question to you all is: Where have you had the best (or worst) experiences selling your used phones?

I'm really interested in hearing about:

• Specific platforms or methods you've used (e.g., eBay, Swappa, Facebook Marketplace, carrier trade-in, local buy/sell groups, etc.).

• Your personal recommendations and why you'd suggest them.

• The positives you experienced (e.g., good price, ease of transaction, quick payment).

• The pitfalls or downsides you encountered (e.g., low offers, scams, time-consuming process, shipping hassles, condition disputes).

Thanks in advance!