I would recommend selling it locally as you can get more money out of it that way. I have used FB marketplace - not the easiest as you have to deal with lowballers, but no fees and low risk (you meet at a public place and get cash in hand). Ebay fees and their scammers there makes it hard as Ebay always favors buyers. Swappa is also great if you want to increase the buyer pool, but has fees. Safest bet is Swappa. I have personally sold several AWs locally. I was new to AWs and went through multiple (SE gold, SE space gray, S6 aluminum space gray) before finally settling with S6 SS. I was out of return windows for all of them as I tried them out for a few weeks. Sold all of them locally and didn't lose more than 20%. So still lost money due to my inability to decide, but not as much as a trade-in.