[masraum]

Most wood working types that want to build a more traditional top will glue a bunch of wood together with the cheapest option being southern yellow pine, and more traditional and expensive options being maple and other hardwoods.

I've seen plywood used. I'd recommend using multiple layers for heft/rigidity. I've also seen folks build a bench and then use MDF as the top. I think the pros are that it's very dimensionally stable and flat, and I think it's usually screwed down as a top layer over something else so that when it gets beat up, it can be easily replaced.

Butcherblock (edge grain) is great (essentially the traditional)

Jack O has a couple made from solid core doors.