Interesting comparisons.
Well, neither of those you suggested are quite as practical as a Golf; the Polo is smaller, and only 3 door, and the Scirocco although bigger doesn't have much room in the back for passengers, and even the boot is a bit restrictive.
In terms of performance, they both can be as much fun, but you'll pay a premium for a G40, as they're still very desirable. The Scirocco is not everyones cup of tea, so the prices are lower, but even with the 1.8 carb engine are quite quick, you'll have to hunt round for a good example with a decent engine though because less have survived.
That said, there's nothing wrong with being different. There are plenty of modded Polos and Golfs around, but not so many Sciroccos.
How about a smoothed, clean lines, Rocco with a 2.0 16v engine, uprated brakes, lowered on nice alloys with a corrado or even a TT interior?