Complex oscillators come in all types and is a really wide category... it's basically everything that's not based on basic oscillator shapes and generation techniques. There are always exceptions, so don't take that as an absolute definition.
Complex oscillators offer some very interesting sounds and development of those sounds right out of the box. But if you stack enough modules together, you can get some very complex sounds out of traditional oscillators.
I think it all comes down to whatever blows your skirt up. I have a Rubicon 2. It's through-zero and I like it. But there's a lot to be said for digital modules, wavetable modules, phase, etc.
What brush would you like to paint with?