but I can't find a straight simple answer.
Probably because the question is not as simple as it seems.
We are looking for different things from our drinks than each other. The water seems the (almost) unanimously agreed bit, after that we dont have the same requirements. The special cycling "performance aids" are designed for all out racers and (in my opinion) wasted on tourers like myself.
In your case you possibly need nothing more added to your water than something that makes it palatable for you to drink on the rides. In my case that is just my favourite cordial, the likes of High5 are disgusting to me and include things that I always avoid in foodstuffs yet if they are similar to someone else's normal drinks they will be happy enough with them.
If you start finding that you are getting cramps then you can look into taking something to counter that but only a minority of us suffer from cramps and it probably isnt worth considering unless it happens to you.
I have never noticed a sugar rush from my drinks, I have the cordial fairly dilute and take a few mouthfulls at a time so it isnt a lot of sugar hitting my system, just a small trickle. Some quick calculations say it is about 100 calories of simple sugars in 750cc of water over about 2 hours.
I had never considered its energy content before and was surprised how much it is.