Looks wise, the pagani for me as well followed by the mclaren, 918, koenigsegg and then the ferrari... this is going to sound weird but the ferrari while still iconic and beautiful, looks, to me and just in this cluster, the most predictable and mundane. Their pedigree like Porsche is of course unrivalled. To use a horological analogy, its like Patek and Lange. I tend to prefer Lange over Patek but can't afford either.
The One : 1 is a technological and engineering marvel albeit "untested". The so called perfect power to weight ratio.