In general, I prefer gels to chews (with the exception of the Power Bar Gel Blast chews). They go down easy, without the extra energy and conentration that it takes to chew while running while not biting your tongue. A drawback is that they tend to be super sweet... almost sickeningly sweet sometimes. So taking water with it is not only good for digestion of the sugars, but it's also amost necessary. It's nice when it has caffeine, too, for its performance-boosting effects (http://sweatscience.com/caffeine-ergogenic-aid-vs-jonesing-for-a-fix/). It's also pretty easy to access... rip off the top and suck. It's dispoable. You get a straightforward 100cal per pack. I usually can't take a whole pack at a time... just half a pack, usually. But that's just me... so I have to save the rest of it in my pocket for later.
Gels that I've tried...
http://www.irunfar.com/2008/12/gu-roctane-review.html). They were all good. I think I liked coffee the best out of those four.
Tasted good. Really, if I said anything about how much the vitamins or the caffeine affected me, it'd be BS without a big sample size of tests in controlled conditions. So all I can really say is whether I liked the taste, and how easy it was to open. Other than that, I can only just cite websites about the effects of those performance/recovery enhancers.
Chews get hard when it' cold, making it very hard to chew. Even when it's not cold, it sticks to your teeth. It's also pretty sweet, so you need to wash it down with water. It is less messy for your hands (not for your teeth) than the gels. And its portion control is nice.... usually 6 chews per pack. So you can access them quickly and often, if you so choose. The exception to the sticky issue is the Power Bar Gel Blasts, which has a powdery surface and more solid chew, making it not sticky in your mouth. The Gel Blasts are also not sickeningly sweet and are rather nice and just tangy enough to be delightful.
Clif Shot Bloks:
Shot bloks come in two packaging types. That gives you some flexibility if your pockets are better suited for one or the other. The long style is the newer one, and I perhaps prefer that one a bit more, since you don't necessarily have to touch multiple bloks with your hands to pick one. I've had multiple flavors: margarita (with extra sodium), black cherry (perhaps my favorite), cola (also good).
To me, these are not much different than the Bloks. Sticky and very sweet.
Power Bar Gel Blast:
Jelly Belly Sport Beans:
On training runs, I don't like to carry liquids, since it adds to weight and pounding. So I only really use these when I'm a) in races, or b) biking. The normal concentrations are supposedly ideal for ingesting the most carbs (to concentrated, and digestion actually slows down, too diluted, and you don't get as much as you potentially could). However, I find them to be too sweet, so I dilute it... maybe about 2:1 drink:water. It's most comfortable to me this way. During races, I have to wash down my sports drinks with water. I think if your body wants it that way, go ahead and do it, even if studies say that there's some other ideal concentration.
Gatorade and Powerade:
I haven't tried these except in races, so I can't say very much about them. They're fine to me, as long as they don't have High Fructose Corn Syrup. There are different kinds, like special endurance formulas and special this and that, but I just take what they give me.
There are different forms of protein. You definitely should take some after hard workouts, but there's also science to suggest that it's good during long workouts (http://www.active.com/running/Articles/Fueling_for_peak_marathon_performance.htm).
Body Fortress Whey Powder:
As you can see, this doc was put forth by the dairy council, but there are enough studies saying the same thing, plus my own experience, so that I'm satisfied.
Sustained Energy by Hammer:
Maybe it was that I didn't make a large quantity, but it was hard to suck it out. Maybe it was the fact that it was more of a paste. The flask is probably good for either liquids or gels. Ummm... I'm kind of tempted to just buy normal gels, since they are more portioned out and easier to suck out. The one I have can hold 4 oz. It does give me the option of mixing my own stuff in the future, though.
Tastes sooo good. It's like those malt balls, with the perfect consistency and taste. Protein and sugar. I'll probably use this in my marathon, mostly for the protein, since I'll have plenty of sugar from the Gatorade Endurance that the race will provide. I'd eat this just to eat it, it's so good. Expensive, though... $3ish. I've only had the Cookies & Cream flavor, and I'm a big fan.