I think which is best is completely a matter of preference, that's why I gave some pros and cons of each. I think I had the most fun with Romanesco: it's a really unique and beautiful vegetable, though the fact that it doesn't keep producing made it hard to justify in my small space.
In his Idea earlier this week,
@dave recommended Waltham. I've never grown it, though the characteristics sound similar to Calabrese, which was my most productive variety.
I'm curious to hear which varieties other members have grown. What did you like and dislike about them?