The Mk2 16v is a fine car, and if you have a later one, you won't even be that short of modern conveniences.
The mk3 vr6 will be quicker than the Mk2 16v but not by a huge amount because the Mk3 is heavier.
I had a Mk3 16v and a Mk2 16v and in terms of performance, there's not a great deal in it, the Mk2 does feel more raw and slightly nippier round the bends, but then it's a little lighter and the Mk3 was known for softer suspension. the mk3 interior is more comfortable and modern, but it's all up to personal taste.
If you want to stick with the Mk2, but want more power for a better 0-60, spend some cash on some engine mods. How about a performance Cam, or twin weber carbs? Lightened fly wheel, or perhaps lose weight from the entire car ? Better exhaust or a short shift gear changer or even a gearbox with different ratios to improve the 0-60 ?
It's all personal really, do you have the money for a new car or serious mods? Are you a real Mk2 enthusiast or do you like the Mk3 or Corrado more? Do you want the modern creature comforts or is it all about speed/performance/handling ? Are you mechanically minded enough to do the mods yourself?