Caffeine does NOTHING for me.
Ginseng & Taurine make me feel like complete shit
Vitamin B12 gives me a decent boost without crashing
I've tried Rockstars and the like...they all just make me feel terrible. Coffee doesn't do anything for me. Redline makes my heartrate skyrocket and makes me stay up all night, but I feel like committing *******. The only supplement that I have ever enjoyed using is the limited production Zipfizz energy shots (pre-mixed shots, not the powder variety). They focused on Vitamin B12 (42,000% of your daily needs!), so I would get a decent boost and no crash later on. I drank one a day every day for about a year and a half, when they stopped producing them. That was a sad day.
At my work, everyone goes through like 3-4 rockstars a day. I consume no energy supplements besides the caffeine in the pop I drink (unless I just drink Sierra Mist that day). The funny thing is, I consistently have more energy than everyone else. It doesn't matter if I got 3 hours of sleep that day, I'm always more energetic. Those energy drinks are a joke.