a9 II

Sony a9ii .. cos it gives you a wider lens choice from third party like Sigma and Tamron on a limited budget. a9ii is still a very capable camera for what you intend to do.

My only issue with the getting the lens first, is that with a crop sensor, the 100-500 may be too much reach to cover the action easily. So I would go with the 100-400 recommendation there. I suggested the a9/a9ii because of the stacked sensor, blackout free EVF, and the still awesome autofocus capa

a9 and a9ii have the same sensor, if you are on a budget look for a clean used a9... it's $1100-$1600 here in the states... the best sports bargain in any mount, by a long shot. set it up for back-button af. the downside is that it's limited to 15fps with 3rd-party glass, like all sony bodies.

I'm a Sony shooter and can vouch for their ecosystem. I have an A7SIII (same tech as the FX3), an A9II and an A7III. I also use the FX3 and the FX6 from time to time. The A7SIII is insanely good in low-light and has one of the best rolling shutter specs in its class. The A7SIII is great as a hybrid