We cook with all of them pretty regularly, but Id have to say zucchini most frequently of those three. Always on the hunt for new and delicious recipes.
Here’s my favorite soup using Zucchini. It’s adapted from a recipe in the original cookbook ‘Laurel’s Kitchen’ that I found decades ago. (I’m no longer strictly vegetarian, and sometimes I use chicken stock or half chicken stock and half chicken bone broth. But I think I still like the soup better with vegetable stock):
http://www.freerepublic.com/focus/f-chat/3259353/posts