Just get water down your neck mate.
All this fancy shite is just a fad. gets the blood suger up for a bit thats all.
Most are far to high in potassium and sugar, drink that poo and the water you have left will then be drawn away from your working muscles to your gastrointestinal tract in order to break down the suger and you will go down hill from there.
Don't forget to check the ingredients - the Isostar stuff that comes in litre tubs used to have caffeine added. All very well, unless you're doing a sport where that's a disadvantage (ironic - as well as being an IOC banned substance above a certain level, caffeine is also a diuretic).
As for the various readymade "isotonic sports drinks" (e.g. Lucozade), remember that they have to taste nice, or they won't sell. So, no salt, then. They're apparently not too hideous, though.
A lot of the Hi-5 stuff was energy replacement drink, rather than genuine isotonic stuff. Apparently, several people have got rich from the realisation that you can take glucose in bulk at sweetie-money prices before splitting it into litre tubs and charging a fortune, because some gym bunnies are gullible.....
According to one (reliable) dietician, those Nutrigrain Elevenses bars are pretty good stuff in terms of "snacks while sporting".
Best of all, Jungle Juice. Isotonic before we even knew what it means (and the best explanation for why it always tasted nutse - ahhh, hypotonic!)