MD500.
For looks. Its the Lamborghini Countach Poster-boy of Helicopters - it's just not possible to find a sleeker machine. An aesthetically perfect tear-drop shape. Like the Jetranger, its become ubiquitous - and as a 'classic' everything is measured against it. Sure, some EC's are great looking machines, but in my eyes just don't quite compare. Kind of like Japanese sports cars - no matter how good they look, they're still not a Ferrari.
Of course the BO105 doesnt quite have the looks but sure does have the performance.
I'd like to fly the Lynx just because its the fastest - and an empty Chinook or Aircrane because of the size and power.