I like the low carb ones the best I believe it's the purple looking one. I used to get them 3 times a week I don't think it helped my energy but I liked the taste and I felt like it might do something so I drank it anyway. I've never gotten energy from caffeine besides coffee
I used to drink these alot in my twenties I'm not sure if it ever made any difference in my energy level but I used to grab 2 and dump it into a monster after a night of drinking and having to work. Taste is ok.