Depends on the purpose of the drink in question...If it relates to enhancing performance than these drinks have been shown to improve performance by up to 20%, although try to stay away from carbonated ones. There are various makes out there. the hypotonic, isotonic, hypertonic names given to these drinks on the backs of the bottles refer to its osmolallity (ie the carbs and elctrolyte particle concentration). Hypotonic drinks are absorbed into the body quicker than water although contain less carbs. Hypertonic drinks contain more cabrs but are absorbed slower than water. Isotonic drinks contain similar particle concentration to water but have the advantage of more carbs. In theory isotonic drinks are the ideal choice when compromising between rehydration and refuelling. To create your own isotonic drink at home follow this recipe:_
40g - 80g sucrose
1L Warm water
1-1.5g salt
Squash for flavouring
Alternatively
500ml Fruit Juice
500ml Water
1.5g Salt
If you are aiming for just keeping ur energy levels up aim for drinks described as hypertonic as opposed to hypotonic drinks and isotonic drinks which would help in sporting situations.
Reference - Bean A. "The Complete Guide to Sports Nutrition" 4th Ed (2003) A & C Black, London.