There are so many beautiful models of the Lancia. But performance wise, which one is the best?

Currently, l guess the Thesis would be the top performer.In the past,(as far production cars) it would have to be the Delta HF,Stratos HF,Beta Volumex Coupe.
http://lancia.com/

Performance is always subjective, especially in smaller displacement Italian autos such as Lancia/Fiat & any of the many Alfa Romeo's.
One of the best all around Lancia models were the ''Monte Carlos known here in the USA as the ''Scorpion with shared pan & drive component base as in the Fiat X19. The Lancia got great gas mileage, handled like a F1 car, & was light & active in launch & stops. plus, it had serious unique looks & real class, all in a small car package.

l would have to say there were several ''higher-performance'' european only models, but personally none had memorable looks.