I always thought that the Fuji Declaration was one of the coolest single speeds made of chromoly steel, mainly because of its rack mount at the rear.
However, I just found out that the Declaration is made from hi-tensile steel, instead of chromoly. You'll be paying a fairly premium price for the Declaration, if you're paying over $375 for a hi-tensile steel single speed.
Elios 1 = Hi-tensile
Elios 2 = Chromoly