If you’re looking for the best head for your tripod, be sure to check out Really Right Stuff’s BH-55LR ballhead. I consider it to be one of the best ballheads in the world… read the reviews on their site (and this one from outbackphoto.com) and you’ll find that many experts agree. I’ve been using this ballhead since November of last year and I absolutely love it! It’s the most precise, sturdy ballhead that is small enough for tripod use that I’ve found.
I am a professional nature photographer and lead photo tours in Yellowstone Park. I had the BH 55 RRS ballhead and returned it. Because of the fact that if you have your camera on the head in the vertical position with your left hand on the lens (like almost all photographers I know)you have to take your hand off of the lens and bring it all the way around behind the camera to loosen or tighten the ballhead. Arca Swiss and Really Right Stuff are not this way. They are much faster and more efficent to use.
Sorry! In that last comment meant to say that Kirk and Arca Swiss are faster to use, not Really Right Stuff.