Casrer druid - nature fang or storm druid?

[Just a Guess]

The nature fang gets +1 to class ability DCs, which includes spells.
The storm druid gets domain casting.
Which would you suggest?

[Exguardi]

Levels 9 and 11 on the Storm Druid are the sweet spot, granting two domains and spontaneous Chain Lightning respectively. I think that overall Storm Druid is a stronger choice if you are going pure "caster," as the increased DCs are balanced against infinite-duration 100-foot perfect Flight, or Earth Glide, or even the immense CON increase of a Water Elemental.

Or animal forms, I guess, but I like elemental forms better for a caster. The ability to become incredibly small with wildshape can be super useful for a stealthy caster druid.

[Taenia]

Keep in mind Nature's Fang druid loses wild shape which is a huge hit to druid power and versatility.

[Imbicatus]

Urban Druid is also great for a caster druid. You get spontaneous domain casting, access to generally better domains than storm druid, and at will alter self at 6th level, while still getting (delayed) access to wild shape.