Not about pencils, but those two brands were my favorite when hand drawing PCBs on copper boards. I had used before a dedicated PCB marker (can't recall the name, ink was blue and it had a spare white tip on the back, they didn't last much) which left all sorts of unwanted marks while making nearly impossible drawing thin lines, aside costing like 5x. One day I brought home some Faber Castell and Staedtler water resistant (this is important!) fine tipped markers and they opened a new world: sub-mm lines, well defined traces and very easy to use without leaving marks, almost like drawing on a piece of cardboard, and they lasted a lot and cost a lot less. Clean the surface, then draw gently so you give time to the ink to transfer to the surface, then correct if needed using common alcohol on a swab.

I have one of those still working; bought probably in the mid 90s.