When it comes to vegetables, the darker the better. Dark and steamed, steaming softens the veg without pulling all the good stuff out. Full on boiling basically cooks out the nutrients (which is good for things like stock!). Don't tell your self you're eating veg when eating potatoes or other starchy vegetables. Starchy below ground veg contain rapidly absorbed carbs, not good.
The colored ones have many types of carotenoid [like vitamin A] & flavonoids [phytochemicals] that prevent all kinds of unhappy events (cancer, heart & vascular trouble, strokes, etc). Especially the "above-ground" portions of veggies has fiber, slow-release energy and no fat. Cabbage, broccoli & Brussels sprouts are anti-cancer. Garlic is probably heart-healthy.