Pick 6502/NMOS from the language list.
This has slightly more traditional syntax, and some of the opcode descriptions are improved, though I'm not sure this makes a huge difference.
Illegal opcodes aren't supported yet.
Pick 6502/CMOS from the language list.
This supports the basic set of CMOS instructions only.
This appears as 6502 Constant Reference Analyzer in the analysis
options.
Does a better job of handling indexed addressing. The default analysis has a bad habit of treating indexed addressing as a reference to the indexed address, whereas for most 6502 code it should be treated as a reference to the base address.
The (zp,X) addressing mode is still treated as a reference to
zp+X.
The 6502 analyzer
The repo contains an Eclipse project. Presumably it's possible to make
it generate a .jar file for easy installation, but I don't know how,
so for now: import Eclipse project into your workspace, and run Ghidra
from inside Eclipse.
Ghidra should build the CPU descriptions automatically, but I've found
this a bit flaky. You can build them by running ant in the data
folder.
Known issues: https://github.com/tom-seddon/Ghidra6502/issues