Who, do you think, designs the best looking tube-based devices?

I would go with Air Tight and Shindo for my tastes. I like to see the tubes glow. Don't know why you would want to have a tube amp stuck in a box.

It is also funny how brands go through phases of popularity. I still love the classic look of the older Jolida amps that were once the rage (and great sounding). They don't make them like that any more and we have gone through a few rounds of other brands becoming popular and then falling off, even though they continue to make great gear.

Pathos
Can’t remember the name of ones that the form looked like sea creatures, with eyes, etc.
Einstein
Unison Research/Unico 

Octave  & BAT

Border Patrol, but I am biased since my amp is a Border Patrol  SE300b

When I was looking, Pathos (Italia!) and Vincent (demure, but with a peek inside the boudoir) were both alluring, but in the end I went with Quicksilver, but not for looks. As I look over the variations, there are lots of nice boxes (some with tubes jutting out, others with fancy metal coffins), but they all reduce of a pedestrian, utilitarian look, at least to me. Yes, a nice wood box doesn't hurt, but from a design standpoint, it's not much of an aesthetic accomplishment. Electronluv is amazing -- almost dangerously good looking.