Oh, then yeah, if you're in a hurry, then sure, go ahead and buy now.
One thing I will say is that Intel seems to change its socket and chipset compatibility constantly, so you'll have a limited upgrade path. Meanwhile, AMD has promised to support AM4 until 2020. (I'm not sure if that's until January 1, 2020 or December 31, 20202.)
So if you buy a Ryzen, you'll have a more certain upgrade path. By contrast, if you go Intel, you might find that next year, Intel has released a new socket and chipset that isn't backwards compatible with the previous one.
Intel processors tend to have higher clock speeds and IPC (instructions per clock), while AMD Ryzen tends to have more cores for a given price range. So for the price of a Core i5-9600K with 6 cores at 4.6 GHz boost, you could also get a Ryzen 7 2700 with 8 cores at 4.1 GHz boost. Typically, the Intel will be faster at lightly-threaded applications where clock speed is more important than threads, whereas the Ryzen will be faster at more heavily-threaded applications where more threads are more important than clock speed. If you're running a program that can take advantage of 8 cores, then the Ryzen's extra 2 cores more than make up for its lower clock speed. Benchmarks typically show Intel winning at games while AMD wins at things like scientific programs, encoding, and video editing. But they're both pretty close, neck-and-neck.
Here's a review where the Core i5-9600K and Ryzen 7 2700X appear in the same chart. (The 2700X is just a 2700 with a slightly higher turbo clock of 4.3 GHz.)
https://www.anandtech.com/show/13400/intel-9th-gen-core-i9-9900k-i7-9700k-i5-9600k-review
So the Core i5-9600K looks like it would be plenty good. But just FYI, that's what AMD is up to.
If you decide to go AMD, your chipset choices are X470 and B450. The two are almost identical, just with a slightly different number of PCIe lanes and SATA ports. So if you want to save money, check out Ryzen + B450 and compare the prices to your Intel parts. https://www.kitguru.net/tech-news/leo-waldock/amd-b450-chipset-preview-x470-features-at-a-lower-price/