There are a lot of messaging frameworks out there to choose from, but I take a bottom up approach: I start with the differentiators and proof points and then build my elevator pitch, value prop statements and long descriptions from those foundational components. I also use the rule of 3 for my differentiators and proof points. If you find yourself with a laundry list of differentiators or proof points, start looking for similiarities among those components to create larger "buckets" so that your audience has an easier time remembering your message.
The trifecta of short-form published writing, long-form writing, and enablement materials always does the trick for me. If I can see the candidate has written a great feature-related blog post or one-pager, a positioning and differentiation narrative, and slides that cue up best practices, then I'm a happy hiring manager.
These are all interrelated.
Messaging: Includes value propositions, your story, and pitch. Also includes things like naming, alternatives, and taglines.
Value Proposition: These are the top benefits you want to focus on for your product based on customer and competitive unput
Pitch & Story: These should be the same. Your pitch about the world before your product, the current approach, why it’s bad, the business consequences, and the new world with your product should tell a story. This story should hit on your main messaging points and value propositions.
Hope that helps!
Case studies and writing samples signal to me that you can do the job you are asked to do but they rarely make a candidate stand out (unless the content is really bad!) I do think long-form writing samples have their place - they should show that you can communicate well and that you can possess critical thinking skills.
But what makes a great candidate stand out for me, far more than anything, is a strategic mindset and an ability to provide evidence of outcomes during the interview. I'd focus on this more than on the portfolio. I go into how to do this in more detail in other questions.
I'm out of time, but real quick, Patagonia and Apple are favorites of mine. They both have brands that stand for something, and they continually demonstrate their commitment to their vision in their actions. On top of that, they both have high-quality products.
I believe that product and marketing are two sides of the same coin–you can't be a successful, sustainable business without one or the other.