It depends, what do you usually spin? I have a Z2 and I've used an S4. I love my Z2, but that's because I use turntables and scratch, it's also great because it has all the functions my X1 had except for the 6 FX knobs. If you don't plan on using Turn tables or CDJs your best best is probably the S4, you'll get more functions like the pitch control, you have the jog wheels and full control of all 4 channels.
