I haven't had mine long enough for any dirt to accumulate. My instinct was to go for black or a dark colour, but I'm trying to change that particular aspect of me that sees clothes and accessories in shades of black.
I surprised myself by not getting blue, my usual go-to colour when forced. For whatever reason my preferences recently are evolving to green (I'm thinking of painting our bedroom/retreat a similar colour).
Cheers,
Marc