Keeping to strictly "beautiful" cars, i'd say either:
Pagani Zonda F Roadster
Alfa Romeo 8C
or Aston Martin V8 Vantage
The Aventador, Zonda R, Aston Vanquish and DBS, etc aren't exactly what i'd call "pretty". They're amazing, crazy, awesome, but not pretty or beautiful designs. Beautiful cars imo should have simple styling not too over the top, nice curves and good lines. Adding too many vents, louvers, etc takes away from how beautiful a car looks. It may still look good, but good in a different way. I consider the Elise a beautiful design, but the Exige is too angry and aggressive to be beautiful, even though I prefer its looks over the Elise.