A good case can be made for corn or potatoes. I like onions just fine, but AFAIK, you cannot create alcohol from them. Corn squeezin’s, sure. Vodka from potatoes, Absolutely! But what do you get from fermented onions? I might have to strike soybeans down as perfect because of this. Also soy without seasoning is an unwholesome thing. You pretty much need onions and chilis to make soy taste right, as a normal food.
I didn’t see anyone mention broccoli. A GREAT vegie! Full or flavor, vits, and minerals. Had at least 13 broccoli chunks for lunch today at Mrs. Chen’s. Served in all kinds of different ways.
We even had a SENTIENT Broccoli from Mars, of all places to find a plant-based civilization!, show up for a while over on the BadAstronomy Board. His name was “Barry”. (Posted some pretty good stuff, too—for a (Martian) broccoli.
Despite my position of the potato being the best vegetable, I must admit that soy beans bring me more joy.
I’m a vegetarian, so things like soy milk, tofu, soy bean curds/soy nuggets/soy burgers, soy bread and soy nuts help bring in protein that I would otherwise miss, and also provide textures which I would not have.