Well the search for a good ballhead can be a slippery slope - and not cheap. Here is a great article - although a little dated.
http://bythom.com/support.htm
I use a Really Right Stuff BH-55 ballhead. It is quite robust and represents quality in all respects. But it is a little heavy and not cheap. My wife uses a Really Right Stuff BH-40 - a lighter and slightly less expensive model that easily handles her D7000 and mid weight lenses like the Nikon 70-200 or Tamron 200-500. We both use L-brackets with our camera bodies and Lever Releases on our ballheads. L-brackets and lever clamps provide easier changes between landscape and portrait orientation.
Markins has nice ballheads. In Europe they are distributed through the Nikonians Pro Shop. The Q20 is their top of the line and the Q10 is similar to the BH-40.
Arca Swiss makes a Z1 that has had good reports. They are a leader in the field.
I've heard some good reports about Benron and Cullman. They make a variety of heads so it depends on the specific model. Which model are you considering of the Cullman? And what is the largest lens you have or plan to own?