3/4 inch plywood.
It is much lighter.
It holds screws way better.
It is more durable.
It doesn't absorb water like a sponge and bloat out.
It is better in every conceivable way except it takes a couple more minutes to sand before priming and painting.
I don't know why anyone would ever use MDF to build anything.
MDF is crap.. make it out of lasagna noodles.. same result..I'm lazy as hell when it comes to arcade projects and not exactly a carpenter, but in the last year and half I've designed and built two entire kitchens from MDF and remodelled several ones before that while keeping most of the old structures. I think that counts. The cabinets and drawers get abused by tenants and kids each day. They are fine. And an arcade cabinet is hardly going to have it worse than a kitchen one on a rent apartment unless your friends are real hooligans.
If you don't want to use plywood (birch would be the best) - use particle board. Its inexpensive and is still better than MDF.
But seriously - you going to spend plenty of money on a machine.. and encase it on something slightly better that corrugated cardboard?
pro tip - listen to people who have built stuff before.. not people who have never built a think and own zero tools..
Kitchens for tenants... Sure.. low cost kitchens..Friggin Bulthaup kitchens ($/€60,000 to $/€100,000 for the cabinetry alone, easily) use MDF.
Our Home Depot MDF that people use to build arcade machines here is crap.
... instead high density (chip) particle board is used. The same stuff they used in making original arcade cabinets.
A couple more things to add about MDF.
It's a great material for a control panel surface. It's density goes a long way in reducing the "drumming" noise that can be an issue with thin and lighter density material. And in a world where heavy CRTs and bulky cabinet structures tend to no longer be the norm, the extra weight of the material can add much needed ballast and stability to free-standing cabinets.
I'm surprised nobody mentioned MDO plywood. I have to order it from my local Home Depot, but I never have problems getting it. Kinda pricey but really smooth and durable.