There is no meaningful head-to-head here: the SC3 Ultimate is 35 Nm of professional-grade hardware on Simucube's newest motor, and the Sport 9 is a 9 Nm entry base at roughly a seventh of the price. One is for pro-level rigs and budgets; the other for a first proper direct drive.
So the only useful advice is to shop your tier. If you need professional torque and the ceiling of build, the SC3 Ultimate delivers it. If you are starting out, the Sport 9 is a good, cheap entry with the Simagic ladder above it. The gulf between them is the point.