First of all, I want to say that these are beautiful gardens. They have a lot of color and much nice flora. But overall, they did not seem to be manicured as well, or organized as well, or as sizable as the other major gardens around Funchal. Despite this, it is a nice place to spend part of a day enjoying the gardens and the views.
If you have only a short time in Madeira to visit gardens... Then the Monte Palace Gardens should be at the top of the list... Second would be the Botanical Gardens... and the Palheiro Gardens would place third.
And if you love orchids... Then Quinta da Boa Vista Gardens should be at the top of your list.
But to tell the truth... You cannot go wrong visiting any of these gardens in Madeira. They are all wonderful.