I use a
SteelCase Leap and it is without a doubt, the sturdiest and most comfortable chair I have ever owned. When you spend 10+ hours a day on your ass some days, it is essential that you have something decent to sit in. One of the best investments I have made.
Herman Millers are great too, but check them out side by side, and there is no doubt that you will go with the SteelCase. the biggest draw back is the weight. This beast weighs 50-lbs easy.