Welcome.
I had an Alfa 156 2.0 Tspark, nice to drive, but just fell to bits. Was so glad to be back in a VW after than.
If you get a Mk3 GTI, you won't be sorry. But get the 16v version as the 8v is a bit under powered.
As a comparison:
Alfa 156 2.0 Tspark - weight 1270kg - 155bhp - 0-60: 8.3sec
Golf GTI 16v - weight 1090kg - 150bhp - 0-60: 8.0sec
I've had both and would definately recommend the GTI over the 156, even if performance is pretty close, the GTI is just feels better built and like it will last and it handles curves better.