I'm planning on getting brigandine/corazzina armor, what cover would be more historical leather or wool canvas. And what would be more durable? In addition how long does my gambeson need to be? Mine only touches the hip bone.

Not sure brigandine's used wool very often. As well the brigandine tends to use a mixture of materials, leather canvas and velvet or some nicer outer layer.

Now if you are talking about the pairs of plates I have seen more often canvas and at times velvet. There is evidence for leather though seemingly alone.

I cannot think of any wool examples though.

RPM

Yeah, I've never seen wool and leather seems to have been rare. Linen/canvas seems to have been the most common material. Wealthy men covered the construction with expensive materials like silk, velvet, satin, sendal, fustian, etc.

Does it make a difference in performance against weapons?

Probably; wool has a pretty low tensile strength. I can imagine rivets being ripped through it pretty easily. Nobody has done any tests comparing the protective capacity of various brig covers.