1. Craigslist is slow. On eBay, you're done in 7 days. It can be pretty hard to get full market value on Craigslist in anywhere near that amount of time, if at all, especially if you're in a smaller city.

2. People on Craigslist are flaky. I have no idea what compels someone to email a seller with interest, schedule a time to view an item, and then just not show up, but they do it all the time. Why even bother?

3. People on Craigslist are needy. On eBay, I list and then I sell. I am selling two items on Craigslist right now. You should see my phone's messaging app. It's full of the unknown numbers of un-serious buyers asking pointless questions they'll never follow up on.

4. People on Craigslist are, well, people. That means I have to meet them somewhere. Arranging that always ends up being more difficult than a trip to the post office.

I view the tradeoff like this:

eBay = simple, easy, fast, but with a nonzero likelihood of total loss

Craigslist = nearly guaranteed to be difficult, slow, and annoying, but with a very low chance of total loss

I don't think it's an easy decision. They are definitely not interchangeable.