If you ask a professional gamer, which processor he will choose for the best gaming experience if not bound by the budget, I am sure most of them will say only one name the i9-9900K, the flagship from the intel in the 9th gen, offering 8 core and 16 thread’s, with base frequency of 3.6 GHz and an all-core turbo boost frequency of 4.6 GHz.
The i9-9900k is a very powerfull chipset, but Intel wants to make it more powerful, they released a limited edition version of the 9900K, named i9-9900KS, in which the core count is same, but the base frequency is of 4 GHz and all core turbo post frequency is of 5 GHz, yes! a freaking 5 GHz in all the cores.
Performance-wise I will drop the benchmarks here, it performs better than the i9-9900K but not by a huge margin, but in nongaming tests like cinebench, 7 zip and test like this, this chip was nowhere near the AMD Ryzen 3900X and was competing with the Ryzen 3700X for most of the part.
However, in terms of gaming benchmark, the case is different, coming at the top of every gaming benchmark, all due to the increased clock speed, which the games take full advantage of.
So if gaming is your utmost priority and you very less multithreaded work like video editing, photoshop, CAD/CAM then i9-9900KS is one of the best available out there, however, it is not something which you should consider if you already own an i9-9900K.
If you do a lot of video editing, photoshop, CAD/CAM, in short, the multithreaded work and gaming is not your priority then go for the Ryzen series as they offer, more performance.
Other specs like PCIe version and all sorts of things like that a similar to the i9-9900K.