Mine is Gatorade. This has been my buddy for years of training. It keeps me fueled and hydrated, powerful enough to meet the challenges I am always faced with my training and other sweat-soaking activities. I really feel the power that it gives me. It's really different from drinking water. Water has no calories and it has, so there's actually an obvious reason for such. I haven't tried any other exercise energy drink; I don't think I would have to.
I use a pre workout drink called Xpand Extreme Pump, then when that is done I'll usually refill my water bottle once or twice with just plain water. I've found it works much better than any of the other energy drinks I use at 5 AM.
During my actual workout, I only actually like to drink water. I only drink gatorades and other power drinks before and after a workout. I just found that I'd get sidecramps and not actually perform as well during a workout when drinking other things than water. Besides, those drinks are meant to replenish your body and for me, it just works better when not drinking them during a workout.
I just drink a lot of water really. I don't really have a workout drink, but I do find myself grabbing a bottle of Gatorade too when water isn't readily available. But I think it's a good thing to have some sort of energy drink while working out since you're exerting a lot of effort on your body and you would want to replenish and help rehydrate your body because after all this things are made for this.
I actually rarely drink any energy drinks, whether I'm exercising or not. When I'm working out either at home or at the gym, I prefer to simply drink water, either plain water or flavored water. I'm not sure of the benefits of the energy drinks but so far I haven't felt the need to drink any.