I think of the static pole as a "drawing board". I literally SAY to myself when I'm switching to static, "back to the drawing board"-because it's where I go to really focus on my basics. I learn new tricks with the static pole and then switch to spin mode. Doing spins I would say is more challenging on static mode.
But then with spin mode, you have to train your body to create shapes and poses using the laws of physics. Sure, you are only posing on spin mode, but you are also controlling the nature of the spin, how fast and slow you go, how to angle your body to flow with the momentum, etc.
I prefer to dance and perform on spinning pole because I think it looks prettier, but ultimately if I've been spending too much time on spin, I still go back to static because I feel it's best to learn BOTH to be a well-rounded pole dancer. Some of the sexiest routines are done with static pole, and I've found more pleasure and versatility in working with both, instead of only one.