Welcome to the forum @Gerry_sully.
I would consider condition and comprehensive service history to be more important than a specific colour or spec when buying a car around 10 years old.
As with any used car, check all the electrics work. Check for accident damage / repairs. If the car has DSG transmission, check that the service history includes details of the DSG oil changes. Don’t necessarily discount a pre-2011 model, provided the service history shows that the timing chain tensioner has been replaced with the latest version. A couple of weak points with many VW’s is water pump failure and leaking thermostat housing, so check for signs of coolant leaks.
Wheels; the optional 18” Monza Shadow alloys fitted to many mk6 GTI’s are diamond cut which are prone to white worm corrosion. Cost of a good quality refurb is around £75 - £80 plus VAT per wheel. Check the rear tyres for stepped / ‘sawtooth’ wear on the inner edge; the increased tyre noise on cars suffering from sawtooth tyre wear can sound like worn wheel bearings.
Xenon headlamps - these are quite rare as they were an expensive option - I think they cost in the region of £1,100. I had them on my mk6 GTD and they were very good, and IMO if you find a car that ticks all the boxes in terms of condition, mileage, service history and it also has the optional xenon headlamps, then that would be an added bonus.
The interior is quite hard wearing, although with the front seats having quite prominent side bolsters, these can be prone to wear, so check these - especially the bolsters on the driver’s seat. If you find a car with leather interior, VW’s leather isn’t the best quality and the leather can become creased and saggy - again, especially on the driver’s seat bolsters.
Bluetooth and DAB were extra cost options so not all cars may have these. The standard radio / CD player had a blue display so looked a little odd as it didn’t match the rest in of the interior lighting (changed to white for 2012 model year). The upgraded optional RCD510 (with 6 disc CD player) and RNS510 (with sat nav) were touchscreen units and the screen illumination matched the rest of the car’s interior lighting and are a nice upgrade on the standard radio / CD player, although will be a little outdated these days in terms of tech.
This ‘sticky’ at the top of the forum board gives details of model year spec changes;
http://www.golfgtiforum.co.uk/index.php?topic=286420.msg2621288#newGood luck with your search. I hope you find a good example.