I like elegance. Beauty is highly subjective, but I think elegance is more focused on simplicity and efficiency - though still tied up to beauty.

Basically; If someone says that something is beautiful, it's pretty much in the eye of the beholder. If someone shows that something is very simple but effective, it's much harder to argue against.

If a line of code can replace a block of code efficiently, while still maintaining readability and cleanness, then that's something I would call elegant code.