@SKK, that link is a great resource. Actually, the comparison should be of dry roasted soybeans to peanuts (next line) -- the soybeans are the crunchy dry ones that are almost weightless. White beans is a good choice, but you want to compare it with boiled soybeans. Soybeans are very high in protein (and it's complete protein) and also high in fat.
"Most nutritious" is tricky! We are balancing protein, fats, carbs, vitamins, minerals... If we eat a variety of healthy foods -- vary the beans, match them with whole grains, eat fresh vegetables in season and pay attention to personal needs and limitations, we'll do well,

I was waiting for Susan G or Anitalectric to post this answer because they are usually spot on. And I am a sucker for questions like this, so I did my little bit of research at http://www.healthaliciousness.com/articles/beans-legumes-highest-protein.php and found that #1 Dry Roasted Soybeans (Edamame) 776 calories per cup 68 grams of protein per cup Protein: 40% Carb: 33% Fat: 20% But look at the calories and fat per cup!

So my vote goes to Boiled White Beans 249 calories per cup 17.4 grams of protein per cup Protein: 10% Carb: 25% Fat: 0.4%