That's subjective, I'm afraid. : P For me the coolest thing about dragons is the "giant reptile-like" appearance.
Some of them fly in our fantasy realm, but not all have the need to do so. Being a t-rex makes you quite safe if you stay on the ground.
Also, in the Empire dragons are not gathering treasures since they are mostly interested in food and expanding their territories, but at the same time their bones are extremely valuable and durable. And while the Imperials don't have stable sources of gold or silver, dragon bones are actually used both in high-level craftsmanship and as the source of money. Killing a dragon is literally like gathering a treasure - you can not only sell its meat, horns, tongue, blood or eyes, but you can also just gather its bones and cut it into small coins.
Of course, to kill a bad boy like this one you need quite a group of suicidal heroes and some advanced technology / traps: