I know I'm going to give a biased answer, as I've been eyeing Cheeky Boy, but personally, I'd go for the Naughty Boy because it has a better, less clumsy shape than Duke, which I think would actually cause discomfort if anything. However, I've read that Naughty Boy et al. are iffy when it comes to shape. Works for some, not for others.
Hope that somewhat helps. I haven't tried either myself, so I won't be much help. Remember, there's the returns policy if you feel that it's not going to give you any pleasure.