DMD vs. GDC vs. LDC

Question

What are the Pros/Cons of the different D Compilers? How is the performance and the standard compliance/D2 support? How well are debuggers supported? How good are the Error mess

Answer 1

DMD is the reference implementation. Only the backend is proprietary, the frontend is open source.
The code generation quality is not that overwhelming. x64 support is just a few months old though.

GDC and LDC are both based on the DMD frontend so it might take some time until a new version of the frontend is merged in.
Since the backends they use are very mature and good the quality of these compilers mainly depends on the glue code which connects frontend and backend.

LDC and GDC are still developed actively, but mainly by just a few guys.
All in all they could use some manpower.