The European Dragon, in it's most recognizable form.
An immense beast, possessing terrible claws, serpentine body, firey breath and the power of flight. In older cases, dragons also spread disease or possess deadly poison. Bluntly put, the Dragon in it's unaltered state represents the amalgamation of the primal fears of mankind, the antagonistic side of nature and chaos, and the perfect test of strength and will to face down a rising hero, striking down what essentially ammounts to a giant deadly vermin. The ultimate ugly snake with legs, if you will.
Their mythological representations are countless, and their symbolism varied enough to fit well into malevolent or benevolent roles.
I like dragons because I'm a huge mythology nerd, and there's nothing more iconic than a Dragon.
Though I classify classic Western and Eastern Dragons as entirely unrelated entities, really only similar on a surface level in my opinion.