Question for gaming and streaming 3600x or 2700x

The 2700x for high quality high bit rate streaming...the 3600x will do ok as long as you keep the bit rate lower...many Twitch streamers prefer more cores over frequency if choosing between the two.

The GPU you use will also play a big role in the performance you get while streaming with either chip.
 
The 2700x is a great cpu...for the GPU Nvidia has better streaming support than AMD...you'd be better off with a 2060 super than the 5600xt. Check out streaming on Nvidia on Youtube...there's plenty of people talking about the Nvidia hardware being much better for streaming.

As far as boards go you should be aware that the VRM on the board is important with high core count Ryzen chips...the below link is a good reference for picking a board with a proper VRM especially if you plan on moving beyond the 2700x down the road.

https://i.redd.it/2iwdy5wrrly31.png