Of the three options now, black and purple will look a bit dark, purple and pink is a bit more colourful (if that's what you're after) but purple and grey is a great combination that will complement most outfits!
Wow! Im glad you guys convinced me to go purple and grey! Thats the one that was my gut feeling. The purple and pink would have been a nice splash of colour but who am I kidding? whenever I get a colourful accessory I always end up selling/returning it!