Hi,
As kcarlile pointed out, 99.9% of the speaker enclosures around the world are made of MDF, because MDF is the most acoustically dense and non-resonant material available other than concrete (using concrete would not be practical).
Real wood is much more prone to resonances than MDF, which is why MDF is so universally used. Manufacturers then add either a synthetic vinyl veneer of simulated wood over the MDF, or a real-wood veneer, as indeed Axiom does if you prefer a real-wood finish. The real-wood veneers cost more, of course, depending on which wood and finish you choose.
By the way, no contest regarding Jamo vs Axiom. Jamo are European and while they've always had handsome real-wood veneered enclosures, the sound quality is definitely colored and not neutral or linear like Axiom.
Regards,
