Personal rankings are always interesting and I tend to agree with most of your choices. A small remark: you forgot the tropical house at Planckendael's Asian section. And in some way also Antwerp got one with the Wintergarden/butterfly garden.
Thanks for your comment and you are correct that I did forget about Planckendael's Tropical House. I'm not able to edit my original post, but that would be the 12th Tropical House (of a substantial size) on my journey and I enjoyed the one at Planckendael. I deliberately didn't include Antwerp's Butterfly House, or Artis's Forest House, or Artis's Butterfly Pavilion, etc., as I tried to focus on only the buildings of a large size and with more than just butterflies.