Where can I see all the CPUs supported by Ghidra?
Does Ghidra support more CPUs than IDA Pro?
Quoting the Ghidra Wiki,
What processors are currently supported?
X86 16/32/64, ARM/AARCH64, PowerPC 32/64/VLE, MIPS 16/32/64/micro, 68xxx, Java / DEX bytecode, PA-RISC, PIC 12/16/17/18/24, Sparc 32/64, CR16C, Z80, 6502, 8051, MSP430, AVR8, AVR32, and variants of these processors.
The latest IDA pro supports more than 60 families of processors. IDA does seem to have the upper hand but that gap is quickly closing in as Ghidra being an open-source tool has the community support. IDA though closed source has been around for a longer time so you would also find plenty of user developed processor modules.
The supported processors are listed in the publicly available source code on GitHub.
Ghidra and IDA Pro both support quite a wide variety of architectures and processors. It's hard for me to tell which one supports more, and I am not sure how meaningful that kind of comparison is.
For more information, see this presentation and associated materials:
It should be noted that adding support for a new processor in Ghidra can be done via Sleigh. Here is an example: Implementing a New CPU Architecture for Ghidra