My judgement was simple, what's the most expensive, should be the best. LOL.
I didn't build my current stand, it was build for me and I don't like the quality. Not the best staining, plywood ends shipped and were sanded down, etc.
I'd never, ever use PT for a stand. In fact I can't think of many places inside I would use PT. Actually I can't think of any place really.
If I'm going to build a stand out of plywood you won't see the plywood ends. If you do it's not built right.
Inabox, even bigger than a 40B you don't need 2x4. You might use it for the legs but horizontal members are just fine with 2x3. If I were to build an open style higher end stand I would probably use 1 x 4 for everything. And it would hold the weight. It's all a matter of the joinery you use.