If I went the intel route, wouldn't the i5 12600k be a better choice at $280 for 10 Cores 16 threads 3.7ghz boost to 4.9gh ?
For at least today's games, it's not going to make much difference, as they don't really tend to heavily utilize that many processor threads. And with a 6600 XT-class GPU, you will likely be limited by graphics performance more often than CPU performance in demanding games, so the higher clocks won't often matter much. Though for future AAA games a few years down the line, it's possible you might see some meaningful benefit from the extra threads and higher clocks. Keep in mind, both processors have 6 traditional cores supporting 12 threads, but the 12600K also includes 4 additional lower-power, single-threaded cores to improve multithreaded performance, so not all the cores are created equal.
I also heard today that AMD is releasing next gen CPU's, so I wonder if my thread will be relevant when those drops.
If you are referring to the Zen 3 refresh parts, like the Ryzen 5600 and 5700X, then it looks like those might be priced roughly similar to their Intel counterparts, at least based on rumored pricing information, so I wouldn't really expect them to offer much better value than Intel's current offerings. There's also the 5800X3D, which may bring more performance to the table, but it sounds like it might be priced around $450. Which arguably isn't worth it for gaming unless someone is pairing it with other very high-end components, as putting that money toward graphics hardware will in most cases offer more gaming performance than what can be gained from a slightly faster CPU.
They also have a more major update coming with their Zen 4 processors, but those won't likely be coming until toward the end of the year, and will likely be targeting the high-end, at least initially. Intel should also be releasing some new CPUs later in the year, though again, I wouldn't expect them for over half a year, and it's hard to say whether they will offer significantly more value than the current models. So, probably not worth considering unless you plan to wait until much later in the year for your build while waiting to see if graphics card prices improve.
One other thing to add, you almost certainly won't see much benefit from getting a $160 cooler for any of these CPUs, so I would go with something costing around a third as much, and putting that money toward components that will actually have an effect on performance.