It really depends! I get my caffeine fix 3 different ways & it just depends on my mood & how long I need to stay up.
Tea- a rich coconut blend/ oolong with a little sugar/ genmaicha. This will work for maybe an hour or two.
Coffee- the type doesn't really matter just because I use lots of cream and lots of sugar. This works for a few hours.
Monster- works like a charm. This puppy works for almost 6 hours on me. It's strong but it's a lifesaver.