I like GoDaddy Auctions better if you're trying to sell to an end user. Since they are the biggest domain registrar in the world, they get a lot of traffic from people looking for a domain name to start a website. They go to GoDaddy and type in the domain they want, and if it's yours that is listed on GD Auctions, the name will pop up and they will see it and be given the chance to buy it. Flippa could never offer this kind of exposure.
From my experience and what I've seen on Flippa, the majority of auctions that are getting a lot of bids and views, are the ones that are getting marketing from outside of Flippa. People will use Flippa as a place to send potential buyers to compete and bid on the a domain. But even with Flippas growing popularity, listing there still doesn't seem to get a lot of views.