Sedo vs. Afternic (1.Viewing)

I'm wondering about people's experiences and sales using Sedo vs. Afternic to sell domains.

For those of you who have used both, which do you prefer and why?

I have only sold domains through people contacting my registrar (typically WHC) or via Godaddy (domains were unlisted).

I haven't sold a domain name using aforementioned services yet.

Thanks.