Ghidra excels because it is extremely abstract, so new processors can be added at will and automatically have a decompiler, control flow tracing, mostly working assembler, and emulation.
IDA excels because it has been developed for a gazillion years against patterns found in common binaries and has an extremely fast, ergonomic UI and an awesome debugger.
For UI driven reversing against anything that runs on an OS I generally prefer IDA, for anything below that I’m 50/50 on Ghidra, and for anything where IDA doesn’t have a decompiler, Ghidra wins by default.
For plugin development or automated reversing (even pre LLMs, stuff like pattern matching scripts or little evaluators) Ghidra offers a ton of power since you can basically execute the underlying program using PCode, but the APIs are clunky and until recently you really needed to be using Java.
I think what NSA is likely to keep confidential are in-house plugins that are so specialized and/or underengineered that their publication would give away confidential information: stolen and illegitimate secrets (e.g. cryptographic private keys from a game console SDK), or exploits that they intend to deny knowledge of and continue milking, or general strategies and methods (e.g. a tool to "customize" UEFI images, with the implication that they have means to install them on a victim's computer).