I think the F-104 in experimental silver was absolutely striking. The Right Stuff captured the aircraft pretty well, and that scene with Yeager going for the altitude record is inspiring.
I think so many aircraft are beautiful. The designers for Wing Commander did a good job of capturing the emotional feel that a pilot can develop for his fighter craft. I dont know about you guys, but I love the Hornet for many reasons: not just because it was the first WC fighter I flew (the wallpaper with the hornets flying into the sunset here at the CIC is one of my favorite).
I find that different aircraft strike me in different ways. To me, the Supermarine Spitfire was elegant because of its clean and elegant lines. A MiG-25 is beautiful because of its overwhelmingly large engines and the evident clarity in its purpose and design.
Of all the various and unique aircraft out there, I must admit that nothing ever quite took my breath away as the first time I looked up and saw a B-17 lumbering slowly through the sky. Maybe it was the sound and smell of those radials, or just knowing what the crews went through...I wouldn't call the plane beautiful aesthetically. Still, something about that moment never quite escapes me.