I need some new tyres for my GTI soon and was with Protyre motorsport who provide tyre support most of the race series in the UK, e.g BMW, Porsche etc and know a thoing or two about tyres, also the main importer for kumho, michelin etc.
There view on the best (performance, handling, life) tyre for a modified Golf GTI - non track use - Michelinpilot sport 3, but a bit pricey (their retail was about £90 from memory) and almost as good, slightly better life and better wet performance was conti sport contact 3, and their price for these was about 77 / 78 from memory. I am definitely going conti sport contact 3 in a few weeks when I have wrung a bit more wear out of my dunlops, for what it is worth, they agreed with the view of many on this forum that the dunlops really are not the best tyre money can buy