I used to use Preston. I've dropped that in favour of KND hollow. It's about 4 quid for a two metre length, I can see no difference between KND and Preston.
As for Hydro I have in the past used it, as good has any other elastic. I can't justify the price.
If you get some lanolin oil and inject it into hollow elastic it performs in a similar fashion as Hydro. Friends go for this and say it's worth the trouble.
I don't do it myself, it would come under too much messing for me.