I'm a green tea or black tea drinker. I go through 2 or 3 Nalgene bottles (24 oz each) per day at work. I noticed that on weekend, when I'm at home and not brewing tea, I get massive headaches by 10AM. eventually my Mrs figured out that it was caf withdrawal headaches.
I don't like the taste of coffee, even the gourmet stuff it has to be blended with so much sugar and caramel for me to tolerate the flavor. The irony, is that my very diverse extended family is heavy into coffee. One side of the fam has a coffee plantation in South Am, the other side of the fam drink the Armenian Coffee (Surj) or as hijacked on Wikipedia, Turkish Coffee. It's served in a tiny expresso cup, the thickness of sludge, and it's supposed to have about a quarter inch of ground left at the bottom of the cup. This stuff is hardcore coffee. Mediterranean peeps put away 4-6 tiny cups every day. You haven't had serious coffee caffeine, until you've had proper Armenian coffee (Surj)
In my teen years, I used to put away 6 to 12 Coca Cola cans per day. Now-a-days, I may have 1 Coke every 6 months, and I feel the caf racing through my veins, and I start talking really fast.