Which material sounds better for speakers construction? Wood, Ply or MDF?

Most speaker companies will not build their speakers out of solid wood because the expense would be to high

poppycock. There are speakers that cost 500k. There are people that buy them. 

Logic. Never was your strong suit.

@invictus... you clearly don't I am a professional musician  Not a single solitary vintage marshall or fender cabinet is made of plywood, MDF, or particleboard. They are almost exclusively made of Birch.  So you can flap your gums all you want but the actual fucking MUSIC is made with solid wood instruments, solid wood cabinets etc... END OF STORY

Helomech, you make a lot of good points, well done.  

Its funny everyone gets caught up in cabinet shape, wood or not, shape etc, when the room you put the speakers in makes far more tonal difference than the cabinet.  AS you move up the quality and lower the noise floor some of these tiny differences like metal vs wood and other small details start adding up so they do matter.  But for most, at home or the studio, the room is the issue that divides great sound from just okay sound.  
Brad

 I was once in prison and made homemade speakers on the cell block for people... I used layers of hardback books to make the boxes and made my cones From drawing paper, used earth magnets and my coil wire I got out of the transformer in an alarm clock radio. I also built dual bridge rectifiers that I tied into the sound chip to double the power going to it. My voice coils were a total of 8 layers thick.. (4 coils)for one speaker... (2 coils for left channel and 2 for the right channel) but mono output.......... Not much to do in there so I spent my time learning .... Just sharing an experience......