This is the 90s/2000s equivalent of being asked if you were a Disney or Warner cartoon fan when I was younger. (Nobody ever asked if you were a Hanna Barbara kid.)

But to answer your question, I watched a shit-ton of both growing up, but I have to say I leaned more towards CN as I got older. Not to say that the Nick shows were bad, but I found myself enjoying the stuff CN was putting out more for the most part. (And when most of the stuff you enjoy is on one network you tend to watch more of it casually compared to tuning into Nick just for Zim and then clicking over to Comedy Central or something.)