I feel like dragons would probably be greed.
Speaking as dragons, in the European traditions (particularly those shaped by Christianity), dragons have been used to represent all of the deadly sins. Each individual dragon varies. But Gluttony is just as big amongst dragons as Greed. And Pride has absolutely been the downfall of a few of them.
A while back, we were working on a board game in which you would play a dragon, and for character creation you'd pick your defining sin, but you'd also rank the others, and they'd give you a set of weaknesses and powers accordingly. Still want to finish that game, just got distracted by writing novels instead.
But, yeah, a single given dragon might represent Pride better than any other monster, but as a whole, Greed, Gluttony, Wrath, and Sloth are a bit stronger amongst the monstrous dragons.
Now, Chinese Lung, however,
might be a good representation of Pride, if the translations we've read are accurate (we're no real authority on them), but we wouldn't call them monsters, and some contend that "dragon" is a Western colonialist label applied to them and not actually what they are. Same may be said of other similar indigenous beings around Eastern Asia and the rest of the world, really.