Before I ever did any long-distance hiking, special drinks weren't very important to me. I was fine with plain water.
On a long-distance hike, having something flavorful to drink was a highlight of my day and really helped me maintain good hydration. Even when thirsty, it can be difficult to force down 20 ounces of plain water, especially if the water is not very cold or doesn't taste good. So drink mixes are a benefit.
I never saw a need for specially formulated performance drinks on the trail. On a long distance hike you're pretty much at peak performance all the time, being so fit. So really, the main reasons for drink mixes, in my opinion, are simply to enhance your ability to hydrate and to just make you happy. Morale is very important on a long hike.
I've heard people describe using pudding to make a shake. I liked pudding as just regular pudding, not as a drink. Butterscotch was my favorite, then banana and lemon were second favorites. A typical package of pudding mix requires about 2 cups of water to prepare, so besides being fulfilling in your stomach and offering calories, it was also a good source of water.
I drank Muscle Milk a couple of times. I liked vanilla and strawberry. I added Emergence-C to vanilla once and it wasn't half bad. Since I didn't have a wide-mouth bottle to drink from most of the time, I had a hard time getting the powder into a bottle so I didn't drink much of it.
My favorite trail drink of all was Crystal Light hydration lemonade with one or two Emergence-C packets added, either tangerine flavor or raspberry. Raspberry Crystal Light with tangerine Emergence-C was pretty good, too.
I liked diet drinks better than sugary ones. If I needed calories, I'd just eat some cookies with my drink. Diet drinks just taste tangier and more refreshing to me.
I also found that by quitting caffeine before hitting the trail, those few times I did have caffeine, it really lit a fire under me. I figured this out after a few times having a cafe breakfast, when a cafe just happened to be close enough for a detour or a quick return to the trail after a town stop. After I realized what a performance enhancement it provided me, I'd carry some chocolate espresso beans or something like that for those days when I really wanted a boost. It really worked, but would not have had any effect if it had been a daily habit.