That's an interesting question... I'm not sure how one would quantify which is more creative, and I certainly wouldn't stay long at a job that has no creative outlet. It's also confounded by the fact that I got my current job because they're using one of my open source projects as part of their core business.
Basically, your hobby projects are probably more freeing and unbounded, but are they more _creative_ than the work you’re be doing in your paid time ?