The AMD Ryzen 7 9800X3D is overall the best chocie.

I totally agree with JrotWeill, the AMD Ryzen 7 9800X3D is definitely the top tier choice if you want zero compromises. It handles high refresh rates like a dream. However, if you want to be a bit more practical with your budget, the AMD Ryzen 7 7800X3D is still an absolute beast. Since you mentioned targeting 4K, the performance gap between those two chips basically disappears because you become GPU bound anyway. The AMD Radeon RX 9070 XT is gonna be doing the heavy lifting at that resolution. Ngl, if you can find that 7800X3D on sale, it might be the smarter move so you can put that extra cash toward more storage or a beefy Corsair RM850x 850W Gold PSU. Just make sure you pair either CPU with some decent RAM like the G.Skill Trident Z5 Neo 32GB DDR5-6000 CL30 to keep things snappy.