A major producer of premium Tonic, says that if up to 3/4 of your GT is Tonic Water, you should really make sure to use the absolute best you can find - and we could not agree more.
Today the market for premium Tonic, has litteraly exploded and you'll now find Tonics for all purposes. And it really pays off, to do a little research and a lot of trial and error, to find just the right Tonic for your Gin and your taste pallets.
Also - notice that some producers of Gin, also make Tonics to perfectly suit their Gin. These are often worth trying with the Gins they have been made for, but remember that this does not mean that any other Tonic, will not work with their Gin.