I’ve used X-Plane for quite a while and I’m a big fan, the whole approach is quite different from the Microsoft sim though, it’s not quite as ‘pretty’ and it feels quite different to fly.

Like MSFS there is a lot of user created content (aircraft, scenery etc) which is of variable quality, some is very good though. I’m not aware of any real air combat add on though although weapons are simulated in avery basic fashion.

There’s a free demo online, give it a go and make your own mind up?