The 2500Kv offerings of the Pro II and Pro III F60 series from T-Motor.
I went back and forth on these tests a few times to make sure the results are as directly comparable as possible given my results didn't match the manufacturers initial performance values in a few spots. I tested the same props back to back immediately in the same environment and triple checked my calibration values, so these results are as accurate as I can possibly get them. The performance difference between these two is marginal at best, but not necessarily in a way that's not meaningful. The extra half millimeter of stator height gives the Pro III a clear torque advantage, showing better performance on the heavier torque loaded props compared to the lighter torque loads. Response curves are virtually identical on most of the props tested, with the Pro III showing a small advantage on the T-Motor 5143 tri-blade and the HQ 5x4x3. The primary takeaway is that the Pro III produces more thrust on heavier torque loaded props at the same response curve as the Pro II, and similar thrust but better response on lighter torque loads. Even with that being said, the margins are extremely small here with only about 2% gains or less in both indicators. The Pro II motor tested a bit low on Kv coming in at 2425kv (which isn't a surprise to anyone who has flown them) while the Pro III tested bang on 2500kv, which means that in general the Pro II is even closer in terms of raw performance metrics. Overall both of these are extremely solid motors and perform well at similar weight. The slightly taller stator size of the Pro III may give it a small advantage in some situations, but both motors remain compelling options.