Same brand, same software, same wheels - so this is a pure torque decision. The R9 V3 is 9 Nm at $299, the value benchmark that proved cheap PC-only bases could compete; the R16 V2 is 16 Nm at $699, the upper-mid rung that turned the R-range into a real ladder. They score identically on our rubric, so you are not buying a better base with the R16, just a much stronger one.
For most drivers 9 Nm is enough, and the R9 V3 is the smart, cheap way onto the MOZA ladder. Step up to the R16 V2 if you run heavy force feedback, drive a lot of high-downforce cars, or you simply want the headroom and can spend the extra $400. Both share the Pit House software and upgrade path, so wheels and accessories carry across whichever you start on.