The AMD Ryzen 9 9900X3D wins in 10 out of 14 comparable specs, with 1 tie. Its biggest advantage is L3 Cache (1322% better).
Core i5-8600K wins in 3 specs (MSRP: 57% better).
Recommendation
Choose Ryzen 9 9900X3D if you want the best overall performance — especially l3 cache.
Choose Core i5-8600K if msrp matters more to you.
