I considered MDF.. for about 15 seconds. I did my office bookshelves (built-in to walls) in MDF last year, and while they're functional, they're still MDF. Just not the same as real wood, either for the fun of building or the finished product. And MDF weights a frickin' ton.
Since I'm designing my own cabinet anyway, I decided to go for the furniture look. I'm building the skeleton in pine, top quality 2x4s split on my table saw in various and sundry ways. Once that's done, I'll be skinning it in oak veneer, with a sold oak top to the game console. And I live on a tree farm -- non-wood would just be wrong.
The design is quasi-defender. I like the monitor tilted a bit (I got a 25" television, working great, for $25 at a yard sale), but still visible to non-players. The coin box area is recessed back, to allow a kid sitting on a stool to be all over the control panel and still have some leg room.
This is going into a game/bar room, but it's an upstairs game room, very much like a livingroom (bright, clean, carpeted), if it weren't for the bar, the foosball table, and the pool table...