What vertical speed at touchdown makes a 'perfect' landing?
I would argue that the way to think of the perfect landing is not in terms of vertical speed but rather in terms of the G-forces involved. 

Thinking in terms of G-force, the perfect force depends on what you're landing on and how long it is. The various conditions I can think of offhand are:


long dry runway, no wind or straight down the runway -- try for a greaser if you want, although arguably a greaser is not the safest landing.
cross wind -- the higher the xwind the more you want a firm touchdown.
short runway -- firm so you will have effective braking.
wet runway -- firm, especially if the runway has standing water. The two times that I blew tires on landing was when there was standing water and I didn't plant it firmly enough. In the first case the tires blew before I used the brakes. It was an F27 and one of our pilots was in back at a window seat. He said the two right wheels never rotated at all. I had touched down with a greaser on a puddle.
carrier -- I once checked out a Navy carrier pilot in a 182. It was really hard for him to flare for a landing, since they don't do that. As I remember, he said that they wanted a 4G landing impact.