I'm not looking at noise normalized results, I'm looking at airflow and noise results at fixed fan speeds. At 1000rpm, the T30 is listed at 26CFM vs. 24.2CFM for the NF-A12x25 (I mistakenly looked at the airflow number for the NF-F12 in my previous post, but the difference isn't
that huge), while the noise measurements at that speed are 30.6dBA vs. 29.1dBA. Now, this doesn't tell us anything at all about the sound signature, which is very significant, but those numbers still show that the T30 delivers noticeably more airflow at the same speed for an unnoticeable increase in noise. It's not a massive difference, but it's clearly there. As for your graph, that's a rather problematic presentation as it relies on unaligned data points that don't correspond with any of the axes - if I didn't know those data points were based on RPM, it would look like you had picked four entirely random measurement points. For a full comparison, we clearly need more data points - 100rpm intervals, for example. But it's still safe to say that the T30 delivers more airflow at 1000rpm for
slightly (and not likely to be noticeably) more noise, while the NF-A12x25 still clearly wins out
below 1000rpm. IMO, either fan will likely be fantastic - and I completely agree with
@Chrispy_'s summary above. There are several good options out there.