For a humorous or lighthearted tone:
* as stubborn a mule: This is a classic and widely understood comparison.
* as stubborn a toddler refusing their vegetables: This highlights the strong-willed nature of young children.
* as stubborn a cat refusing to leave a sunny spot: This compares the subject to a cat known for its independence and love of comfort.
For a more serious or dramatic tone:
* as stubborn a mountain: This emphasizes the unyielding nature of the subject.
* as stubborn a wave against the shore: This emphasizes the relentless and forceful nature of the subject.
* as stubborn a heart set against change: This emphasizes the emotional and psychological resistance of the subject.
For a more specific or descriptive tone:
* as stubborn a rusted hinge: This highlights the unyielding and resistant nature of the subject.
* as stubborn a knot in a rope: This emphasizes the difficulty in untangling or changing the subject.
* as stubborn a stain on a white shirt: This emphasizes the tenacious and difficult-to-remove nature of the subject.
Ultimately, the best completion for the simile "as stubborn a..." will depend on the context and the desired effect.