Right, MK1 - sorry, I quoted for MKII.
Both above are excellent fitments for the MK1, they will look great & perform well. You may have a tiny bit of fender rubbing with 7.5" ET35 and a 205 in front - some do, some don't. Can't really say there's a 'best' from these selections, depends on what you want. If you ever dropped the car with the Pro-Kit/Illumina combo then 17" would probably look nicer and the 40 series tires would deliver extra sharp turn-ins. The overall combo of the stiffer springs/struts and low-pro tires would make for a harsher ride than stock (if you care about such things).
For the 15s you can always cram on 205/50s on the 15s as well so you can have almost the exact performance of the 17s but have a nicer ride because of the thicker sidewall.
Personally, I'd go for 205/50-15s in front & 225/50-15 out back on those nice 15x7 K1s - but that's just me.
