A difficult one ! :)
I voted Black in the end, because the cosmetic of black / chrome/ black on that shape looked like it would be visually and physically more resilient to time and fashion changes.
I genuinely did like the Oxblood - and thought it said 'Boutique' more than the other two ; redolent of Boogie and those horrendously expensive bespoke amps that get thrown at the Larry Carltons and John Mayers of this world.
However, the minute you put a black grille with that Oxblood, it then seems to fall between two chairs somehow. Oxblood with the cloth on the picture ( or similar straw / brown coloured cloth ) would work - and look the part of Boutique, but as Dave said, the black also uniformly leans into what you already sell - and is an enduring classic in it's own right.
The Blonde was also nice, but I felt it would limit it's appeal to exsisiting 'Blonde' users. Here again, I cannot imagine it looking as gorgeous as black would after many years of wear and tear.
All lovely stuff though. 8)