The AMD Ryzen 9 7900X3D wins in 9 out of 14 comparable specs, with 2 ties. Its biggest advantage is L3 Cache (300% better).
Ryzen 7 5700X wins in 3 specs (MSRP: 50% better).
Recommendation
Choose Ryzen 9 7900X3D if you want the best overall performance — especially l3 cache.
Choose Ryzen 7 5700X if msrp matters more to you.
