Downsides & Advantages of: Auctions, Offer/Counter-Offer and Buy Now

Hey guys, I was wondering, based on your experience with buying and selling domains, what are the downsides and advantages of Auctions, Offer/Counter-Offer and Buy Now for selling?

I think a lot of members could also benefit from these insights

Excuse me if this has been already discussed, if so, I would be happy to look at the thread!