I think it is probably unlikely that you are doing either, they have been endlessly cross bred to get the hard white curd of the cauliflower and the size of the broccoli. The purple, green and the hard white varieties are all broccoli now. I suppose you could say that the purple and green are still 'true' broccoli while the white one is a caul-occoli
I prefer cauliflower and I like my veg well-cooked - none of this al dente nonsense! I love cauliflower served up in a plain white sauce. Yum! I've never been that keen on broccoli but it's really good for you - full of iron.
This is the hardest decision I've had to make in some time. I love them both separately, mixed or in salads etc. But if strapped with a decision, the winner would be cauliflower, and it would be steamed with butter and salt and pepper.
My favorite way to have cauliflower is to toss it will olive oil and a little salt. Put it in the oven (high heat) until it starts to carmelize. YUMMY! It is like eating candy (well almost) But is really does have a sweeter taste this way.
Added to lots of cheese, rice, green onions, and a really flavorful sausage in a casserole dish...they both fare about the same. Although broccoli wins with more color...then blanch white cauliflower...in my opinion.
I love them both, and enjoy them steamed with lots of butter. However, I am having a new favorite, a recipe I saw on TV and it's reeeeeealy good. I cut the cauliflower into the small florets and chop up the stem and fry them in olive oil until there's a nice brown carmelization on them. Mmmmmmm so good! We have this once a week now.