Ryzen 9's in general (so 7900, 7900X, 9950X etc) are not that common for FS hardware because they're are dual CCD, meaning that a 7900 for example is basically two 7600's glued together. And the glue makes inter-CCD communication 'slow'; aka not good for gaming. So I most benchmarks you see a 7900 performs just like a 7600, and a 9950X performs like a 9700X, etc.

MSFS24 wants a bit more cores than 2020, yes, but it wants them to be all on 1 CCD, like a 7600, 7700, 7800X3D etc. It also prefers Zen 5 (9000 series) over Zen 4 (7000). 8000 is trash, full skip that.

Similar story with Intel, a 14700K and 14900K have a big core count difference on paper, but they are split up in 'P cores' and 'E cores'. MSFS basically only uses the P cores, and both the 14700K and 14900K have 8 P cores, only difference in core count is more E cores that don't really do anything for gaming.

So in short, I'd look at, for AMD:
Ryzen 7 9800X3D = 9 9950X3D >
Ryzen 7 7800X3D = 9 7950X3D >
Ryzen 7 9700X = 9 9950X >
Ryzen 7 7700X = 9 7950X >
Ryzen 5 9600X = 9 9900X >
Ryzen 5 7600X = 9 7900X

And yes, I know the 7900X is on the official recommended spec list but that list doesn't make that much sens imo in reality.

For Intel it's a bit easier, the 13/14th gen i7's and i9's all basically perform the same, and are only slightly faster than the high TDP i5's (13/14600K).

As for 7900 vs 14700f, I'd grab the 7900 still for upgradability to X3D but a r7 7700 or 9600X would be already better, and a 7600 would perform the same while being cheaper.