I hear good things about relentless, 19 year old in the office chugs cans of the stuff daily and swears by it! (I THINK thats a positive endorsement, but reading it back, im not so sure).
Another vote for Relentless. Taste is a bit weird but you get used to it! I read an article last week that said all these energy drinks increase the risk of a stroke or heart attack
Relentless - its about 80p a can in sainsburys, plus you get double the amount for less & it has the sdame caffeine amount per 500 as redbull so your getting double the amount! Plus it tastes exactly the same!