A subject very close to my heart

In my personal opinion the best will always be the original - whatever follows on from that will always share its 'motoring DNA' with the original, and it will always only ever be a continual evolution of the car that broke the mold.
The mk1 will offer the most thrills (for the right and wrong reasons), as its the least dilluted car in the range. We all know that as they've got older, the Golf has got bigger, heavier and softer.
Many see this as a bad thing, and slate VW for loosing the plot, but in my opinion, this is not true.
VW were (and still are) very aware that the original 'recipe' of the mark 1 was bang on. If they had their way, they would still be producing a very similar car, and selling millions of them. But the motoring industry has several factors that will drive a products' evolution beyond what the customer simply wants. As many people have said, insurance and safety laws have shaped the way the golf, and every other mass produced car, has evolved.
A lot of people slate the mk 3, which again, in my opinion, is unfair. The Mk3 GTi was a result of VW's desire to coupe a bigger, more comfortable car than the MK2, but under the pressures of making it less desireable to thieves (so that people could actually insure the thing and therefore buy one!) as well as incorporating safety features such as traction control, ABS, side impact bars, airbags etc, and the creature comforts from larger luxury cars such as air con etc, to try and capture sales from people downsizing from luxury cars.
The phrase 'which is the best GTi?' is always going to be an emotional one, as 'best' is subjective - best at what? In terms of driving thrills, its going to be the Mk1. But the Mk1 has awful brakes, and is very old. Best at effortless cruising (undoubtedly a GT benchmark)? A 6 speed Mk4. but they handle like jelly.
Every one has its strengths and weaknesses, and people will always ignore certain aspects of a car to rant on about the good bits!
I'll finish my essay with one final point. Last year Autocar took a Mk 1 (1.

a Mk2 8v a Mk3 16v and a Mk4 1.8T to a track, to see which was faster.
The result? Lets just say evolution works - The least quick of the day was the Mk1, followed by the Mk2, then the Mk3 with the Mk4 the quickest of the day.