Reference Frame - Mesh Motion

Hello experts,

I am working with AcuSolve tutorial Acu-5000 and Acu 5001. which are using the same model, difference is one is steady state/reference frame and other is transient/mesh motion.

I am wondering which one should i use to represent the rotation of fan-blades? reference frame or mesh motion? and why?

(image below)

Thank in advance!