Without getting into how sulforaphane (the isothiocyanate formed when broccoli cells are crushed) and the organosulfur compounds formed when garlic cells are crushed are quite different, I would point out that one of the two compounds in broccoli (glucoraphanin) is broken down by heat, so cooked broccoli isn't going to be making sulforaphane for you - unless you add some other source of glucoraphanin. Aaaaand... mustard, particularly stone ground mustard has plenty of the stuff. Ditto "wasabi", which in the US, at least, is pretty much horseradish - all of those are mustards.

Finally, I've been growing broccoli sprouts, as they have a lot more of the active compounds than market-stage broccoli. It's pretty easy, using mason jars with ventilated lids. You could also just eat the seeds, but those are full of erucic acid (same as with rapeseed oil, which is why it's refined into canola).

Hope that helps somebody.