I say Q pon but I don't even really know why. Nobody I know says it that way, I wasn't born and raised in an area that says it that way. Looking at the word itself it clearly makes more sense to pronounce it 'coo', but I just don't. It just never comes out that way when I say it!
I say coo-pon but I hear it around here both ways.
My 80 year old Southern dad cracks me up because he says it "Q-pin." Don't know where he got that. He also says "mature" like "ma-tour" and we tease him by asking if he also should be saying "furni-tour" instead of "furniture."