I don't drink energy drinks anymore. I find they don't work that well for me, not in a noticeable way at least, and they have too many calories. Not that I drank them a lot before. I've had them while traveling red eye, and a couple of other occasions, but now I don't even use them for that.
The only one that had a prominent effect on me was a Sobe energy drink. It made me kind of more alert and energetic, and also gave me nightmares (yes, I'm sure it was the drink because a) I never get nightmares and b) I tried it again to see and had nightmares again).