Which ArduCopter FC should I choose?

Hi everyone.

I’ve been flying with ancient ArduCopter firmware and 8-bit APM FC in past. More than 2 years ago. Then i swiched to Betaflight/INav based FCs.

Now I see that ArduPilot firmwares have improved significantly, and have been ported to popular betaflight boards like omnibus, Matek F405 and holybro kakute.

I want to switch back, update my knowledge on ArduCopter, and later move on to learning about integrating ArduCopter and Linux-based ROS copilot computers.

Which flight controller would you recommend me to choose? Should I order some inexpensive FC like Matek F405 and flash it with ArduCopter? Which one is better? Is it possible to integrate them with linux ROS copilots via usb or uart connection? Or should I order a PixHawk/PixRacer FC?

Please give me an advice.
With best regards.