When I helped a friend build a pair of 2Pi tower speakers using MDF. We found that veneer to cover front, top & sides would be more expensive than thin solid wood. We glued up for width and used wood glue to apply on to the MDF. I'd done that with my own speakers and it's stood up to the test of time. Also using water based polyurethane used for flooring helps with humidity. And where I live in the summer is very humid. Just an option among many others for you to figure on.

The sides and top will be veneered in Khaya wood (from the mahogany family I think but not quite as red as many of that family are). Front and rear will be a complementary paint finish that I haven't quite decided upon yet.

Hope you'll provide a pictorial of your speaker build. And, you're going to love hearing what your sweat equity brought forth.
There's some pics here under the heading of 2Pi Towers down the page a little showing what we used on my friends pair of speaker. We used Ash wood. I looked up Khaya wood and that's beautiful looking. It would be stunning. Bet it's costly. But hey, you're going to live with it for a long time. And you only live once. So let the good times roll.