Caffeine withdrawal, out of the many types, is my least favorite to experience.

Nicotine withdrawal (non-tobacco) is nearly unnoticeable, while nicbacco withdrawal can be a little annoying. Although, while I smoked for years, I never smoked more than a pack or two pipes full a week, so perhaps it scales.

Neither compares to the full on pounding headaches, teeth grinding, and occasional auditory hallucinations that can accompany cold turkey, n pots a day caffeine withdrawal.

I rate caffeine easily on par with opiates in terms of the length and discomfort of their withdrawal.