I prefer to drink coffee, it feels really good when I wake up in the morning, then I'm fitter, but I rarely drink coffee during a race, i don't usually have a problem with concentration.
I drink black coffee in the morning, and no caffeinated drinks thereafter. It's usually dark beans, like French roast, that I grind and pour water in the filter myself.
Coffee contains antioxidants and phenolic compounds that play an important role in the prevention of cancer; Reduces the risk of diabetes; is Useful for weight loss: accelerates metabolism and reduces appetite; Stimulates the nervous system, which gives a sense of cheerfulness.
Hot chocolate? :3 but if its got to be one of those, Tea. I think Coffee would make my life much more productive, but I don't like it, I've lived 30 years without it, so its doable haha