In my opinion, producing is harder. It requires knowledge, inspiration and a lot of free time. Producing cannot be learnt, it's like an impulse, or this is how I find it... while DJ-ing can be learnt and improved over the time.
When I see a Producer that goes slowly for the commercial music... I know that his inspiration just got over, or is about to end soon. From that moment on... he just stops creating good music. (I'm talking about trance music/producers here).
Anyway, this is just my opinion.