I'm a Monster fan.
I won’t touch RockStar. RockStar is owned by Michael Savages son.
On a plus note, RockStar is good to drink after a night of heavy boozing because it contains milk thistle which can protect your healthy liver cells and regenerate dead ones. On the other hand, there is so much caffeine in the drink it dehydrates you, fast, so you'll need to drink 2X as much water.