Aluminum vs 3k Carbon fiber board

Hello, I’m planning to change my XZ plate (currently in PLA). I have access to 5mm aluminum and 5mm carbon fiber. What would provide the best results?

Also thinking about changing the YZ plate as well (currently 15mm MDF). Is it a good change for the above materials?

Thank you

5mm aluminum would make a good XZ plate. It’s a bit thin for 10mm M3 screws into the rails, but a washer would easily make up the difference.

The same for the YZ plates. You could then use shorter M5 screws. However, I don’t see any problem with the 15mm MDF. The XZ plates will benefit from a little extra stability, and the flatness offered by aluminum, particularly that part which relies pn both sides. The YZ plates have less need.

Oh, take note that you will need to move your Y belt guides when you change the XZ plates.