GMonster Is the best, it works, and it tastes great, take one almost everyday. NOS tastes like horse piss but it does work, AMP Tastes awful, not as bad as NOS and I find that it doesn't do anything, Rockstar is good also, still prefer my Monster, Full throttle same as AMP. To me Diet Pepsi max does the same as regular Pepsi.
You can get some in small cans like Red Bull, Tag and other but they are the same price as the big cans and you have less.
I like them if your tiered it will wake you up and give you a buzz, I have never experienced the "crash" after it wears out. But then again, I'm 15, maybe they affect you old fart more than us younger people.

Oh and edited to add they don't seem to make nature call more.. lol

Edit #2: If you don;t like the taste associated with some of the energy drinks try the Monster Khaos (orange cans) or M-80 (yellow cans)