Well, if I HAD to choose, I would choose spinach, but not always. My mom makes a very nice broccoli soup which I quite like (for broccoli). When I was younger, three or four, I used to like broccoli quite a lot.
The reason I like spinach more than broccoli is that it is easier to “hide” spinach in food, for example: Mixing spinach in your stew or mixing it in your sweet and sour chicken stir fry. But if I had a choice, I would rather choose cucumber!