I have done a review on 2 types of gels. I used these gels, Clif Bar Energy Gel in vanilla flavour, Louis Garneau Energy Gel in a concord grape/apple flavour.
Review
Clif Bar: The Clif Bar I would say is an awesome tasting gel but for on the trail or even in a race, I think it is too sweet and thick. The thickness of the cliff bar is not that friendly for racing and you have to take in water to make it better. I have tested the Clif Bar in training, races, and spinning classes and I have found that it does what they claim they do, it gives you energy but not as much as other gels.
Sum: The Clif Bar is a good gel and it does what it is supposed to do.
Louis Garneau: The Louis Garneau I think is the best gel out of the two. The flavour of it is nice and it is not too sweet like the Clif Bar. As well the thickness is not too thick and you don't have to take water with it, but water does help. I used this gel in my races, training, and spin classes, I found that the Louis Garneau Gel gave me more energy about 15 minutes after I had it. Out of all the gels I felt like this gel gave me the most boost. I have not taken the Caffeine gels by Louis Garneau so I can not say anything about that.
Sum: The Louis Garneau Gel is the best overall gel out of the three.