Someone is more than welcome to disagree with me, if they have a favorite but...
Electrolytes essentially are a few different chemical elements (sodium and potassium in particular) that are needed to hydrate cells, plus often some kind of sugar, such as dexrose, for additional energy. These most important ingredients will be the same and work the same regardless of what brand that you use. The other ingredients are just flavoring and coloring to make the electrolytes more appealing to the animal and human giving them.
With this said, we bought a bag of the Dumor electrolytes from Tractor Supply and were very happy with the results in keeping the lamb hydrated and keeping his hide good. At $20 for 4.5 lbs of the powder, which is enough to make 11.25 gallons. , it's a LOT cheaper than the brand name electrolytes than cost $5/per little pouch. Our lambs seem to love the taste and will drink it right out of the bucket, so no need to drench.