I'm running Eibach springs with OEM G60 shocks (NLA) - big surprise there...

I had Boge Turbo's and they lasted about 3 months and leaked so were taken off - so a good choice not to fit them IME.
I have been told that Bilstein were an OEM supplier so that would be a good option - if it's true...
Koni seem to be well respected by lots of people but they seem to come at a price... I can't comment on them from experience as the only car I've driven with them on - I only drove for 5 miles and then scrapped it...
I would also consider that it's not just down to the springs and shocks you also have to look at the Tyre option and whether you are going or uprated ARB's which in my experience also have a bearing on the handling, I have these fitted too...
I think you have to look at the "Whole Package" not just one or 2 selected items...
This is worth reading too;
http://www.golfgtiforum.co.uk/index.php?topic=227493.0