Actually, the caffeine levels of “energy drinks” is no more than cola. The mega-doses of B vitimins is probably the most important. A controversially effective ingredient in energy drinks is taurine. Taurine has been shown to lower cholesterol and increase metabolism. But whereas caffeine can cause anxiety, taurine has been shown in animals to lower the metabolic pathways associated in humans with anxiety.
I use various ‘pre workout’ drinks before a lifting session or longer run; but I’m treating the caffeine and the other chemicals (L-carnitine, various amino acids, and such) like what it is- a drug. A drug that has a specific benefits, costs and dangers and is utilized for a specific purpose.
IMHO the important thing is to be intentional of what goes into your body and how what you consume relates to your current and desired health. Not everyone has the same goals to say nothing of the same physiology; some people can consume stuff that I shouldn’t, and vice-versa.