I think IDA's 'killer feature' over Ghidra is supposed to be the debugger. Not disagreeing, I am a Ghidra user myself, just that's the reason I usually see proffered in the Ghidra/IDA flamewar.
That's very true. Ghidra is going to get a debugger soon (there was some activity in the issue tracker about this recently), and already has some amount of dynamic analysis support through its emulator feature. But right now, IDA's debugger is pretty much best-in-class.
I mostly use Ida for exploit development, and have been struggling to find ways to connect the debugger to a proc spawned by pwntools. It’s much easier to use gdb-gef and pwntools directly. I don’t know how much of a killer feature the debugger is to others, but to me ghidra still seems easier to use.