Multiple coffees a day are what keep me focused and I used to have 2-3 sugar free monster energy drinks also so I've cut my caffeine intake a lot. Coffee is safer, much cheaper at he than store bought energy drink addiction and you don't hear of many dying from coffee but the odd one dies from energy drinks.
Coffee speeds up my cognition and seems to improve my accuracy at work and my mental positivity any day but it is addictive too