while i agree that animated weapons are more generally useful, i wouldn't take the other comments to mean that dragons aren't worth using, or that picking dragons is bad.
i've said it before on these forums, but the dragon summon is so tanky, that it can literally facetank the megabosses for you. this is not an exaggeration. against dorudugan, hauane o whe, and belranga, the dragon will literally just be my tank and only when belranga starts getting really fast do i have to worry about uptime. (for this reason, do not pick up dragons on a beckoner; shortening the duration and nerfing the heatlh removes the main benefit of a dragon summon). like boeroer suggests, the size is an asset: against dorudugan i can avoid dorudugan's vacuum attack by just standing behind my dragon - the dragon is wide enough that it body-blocks me from getting sucked into range of dorudugan. (auranic is a whole other kind of fight so the specific nature of the summon isn't so important.)
Plus, as a SC you can always get both animated weapons and dragons if you want. though honestly, however versatile animated weapons are, a dragon still does fine in most situations - spamming tail sweep as soon as the dragon appears will single-handedly end many trash mobs. at this point we're trying to differentiate between S-tier and A++-tier - they're both still really good.