7800X3D for sure.
7800X3D is the sweet spot for a fresh MSFS computer as others have said.
You can pair it with a B650 motherboard, it will save you some cash. The X670 variants add a chipset that only make sense in some specific use cases, and the best boards usually have a B650 variant with ample specs for gaming. Don’t skimp on memory though: get the fastest kit your money can buy.
If you are really budget constrained, you can save a few bucks by reverting to 5800X3D on a previous gen AMD motherboard, with the understanding that this is a platform that is at the end of its lifecycle.
Still good for MSFS today, but restricts your upgrade options in the future. If you currently possess an AM4 motherboard, this might be the most sensible option from a price/performance standpoint.
Intel has good CPUs as well, but the larger cache on the X3D AMD processors is a better choice for MSFS as of now.