Having driven 8v, 16v, 1.8T, GT TDI 150 I would say (echoing the posts of others!)
mk2: more fun on A and B roads, people will admire it, cheap to own and service if you are mechanically competent, you feel like you are driving it as apposed to riding in it
mk4: much better for the motorway or if you do a lot of miles, more refined and quiet, air con! You arrive much fresher after a long journey
Put it this way, I would not swap my mk2 for a mk4, but thats me being sentimental
. I would keep the mk2 and get a something more modern if I had lots of miles to do. The point about reliability is fair enough, but in my experience the mk2 is very reliable if it’s well looked after. I have only had one break down (water leak onto coil) in 9 years and 130K (touching wood now)