Among my possibilities and requirements the C7 was one of the best possibilities (besides the fact that it looks super beautiful IMO), but I got a really good deal on the NH-L9i. I bought from a friend, brand new. He was facing some serious thermal throttling as his brand new build counts with a high TDP CPU which the NH-L9i couldn't handle (one more reason for me to count with you guys to get informed before taking hasty unwise decisions ?). Now that I have it, I rather keeping it and just try to get rid of the Noctua's color scheme (which I never understood anyway - of course it's a matter of personal preferences, but I never had the opportunity to find a beautiful build with those colors inside).
The NF-A9 performs about the same or worse compared to the stock NF-A9x14 on the NH-L9i. The NF-B9 is worse but should still perform fine.
https://infogram.com/official-sffn-cpu-cooler-chart-1hmr6gyjwkz96nl?live
https://smallformfactor.net/forum/threads/thicker-fan-on-noctua-nh-l9i.6176/
https://www.reddit.com/r/sffpc/comments/92vbqv/s4_mini_with_l9i_heatsink_nfa9x14_vs_nf_b9_redux/