There should only be two blues. The early ones are Royal Sapphire and the later Strathcaron. If you look at photos then yes Strathcaron blues always seems different, in the flesh there are the same. I would go with the blue, there are so many silver ones about. The grey is also nice.
On the VW/Audi front I would say there are not above average in reliability. Certainly not in JD power or Which? studies. I know people with A3, A4, S3, Bora, Golf and Polo and all have had problems. The 1.8T engine is very troublesome, with poor dump valves and the ignition system is weak. The dealers never seems to fix the problems on the first go either.