Spongebob is undoubtably better, but far too juvenile for me these days to watch outside of babysitting duties. In truth, I remember very little of Rocko, so I can't speak for how it holds up, but I do recall sitting through episodes of Hey Arnold and DURRR! Real Monsters to catch it, so I hope it was worth it.
It's weird that I can remember more of the shows I couldn't stand - like David the fucking Gnome and the Smurfs - than the ones I actually liked.