I can’t comment on the Mk1, but I’ve had a couple of Mk2, a Mk3 and now a Mk4 Jazz and in my opinion, each one was an improvement on the previous car.
So, I’m afraid it all comes down, to what you can afford, but again in my opinion the Mk4, is a vast improvement on the previous cars, not least in runnings cost, where over 5000 miles I have averaged over 68mpg, with my Mk3 I was lucky to average 55mpg over similar journeys.
Yes, there are one or two ‘quirks’ in the car, like having to disable RDMS at the start of each journey, but I can live with that, given the overall improvement.