Few stores will buy an item outright, but any that offer this usually make it very clear that this is a good way to lose a significant portion of the value of your item. If you need the cash quick, this is your option - but you will get pennies on the dollar.
Consignment is easy enough, depending on the store. Most reputable shops have a strong online presence and can reach a national audience, they also have the experience dealing with shipping, valuation, etc. But, you pay for that convenience - often upwards of 40% of the sale price will go towards the store dealing with the sale. Some shops are better than others when it comes to consignment sales, do your homework and ask lots of questions.
Private sales are... interesting. Sure, you get the entire sale price in your back pocket - but you deal with all of the hassle involved in selling an item. CGN may be better than the average marketplace, but it's not really any different than selling on a platform like Facebook Marketplace, being that you'll see all kinds passing through.
Pick your poison, there are pros and cons with each avenue.