Pentel Kerry http://www.amazon.com/Pentel-Mechanical-Pencil-Metallic-P1035A/dp/B0006SW6YO

I have had mine for nearly 12 years and is has served me extremely well. Don't be turned off by the capped design. It keeps it pocket safe and allows for a fixed point when being used.

I think the Pentel Kerry is comfortable, if you don't mind having a pencil that looks somewhat like a pen. The balance is very good and the barrel is a little wider than most. Some people have complained that it's slippery if your hands get too sweaty, so that could be a factor.