What video card will you be running? The thing people forget is most of the reviewers are running rtx 2080Ti cards. Some reviews do the RTX 2080 which shows a smaller difference to the point really paying ~$200 more for gaming performance doesnt make sense.
So if you want to save some money get the 3700x, you will be happy with it. It will do all you need it to do well, especially if you don't have a top of the line graphics card to see the difference.
If you happen to run a rtx 2080Ti , then go with 9900k if gaming is your biggest importance. If you plan to do video editing or other content creation, streaming, pretty much anything else the 3900x is a better buy at the price point.
Also point out to overclock to 5ghz you need water cooling or a top of the line air cooler. So that is an added cost.
For you I would take that 200 and perhaps get a m2 NVME ssd and more RAM. That would make your whole experience a lot better.