Best is subjective since many blogs do different things.
For example Mike Berkens is a hugely successful domain investor but thedomains.com is not about him sharing his secrets and techniques for being a successful domainer. Still a good blog.
DomainShane,MorganLinton,Elliot Silver all share personal strategy and info that is beneficial to someone trying to make money in the domain business.
Ron Jackson from DN Journal is the Godfather of Domain Publishing imo.
Rick Schwartz gives insight that only someone in the business as long as him can give. His post about how much his names have made parked like Porno.com making $15 million was informative.
At HybridDomainer we try to have a wide array of topics from News to stats to interviews to entertainment.
I read all of the above daily, I read plenty of others and usually check the headlines of every blog on domainsville everyday.