The short answer
HelloFresh Australia ran a three way test of Trustpilot reviews against Instagram photographs of food and Instagram photographs of people. This post shows all three and asks readers to guess rather than publishing the winner.

Here's an interesting split test currently being run by HelloFresh Australia on one of their SEM Landing Pages. They are trying out three different approaches to social proof. The first (their control) highlights formal customer reviews from Trustpilot with stars:

The second variation highlights Instagram posts from customers, highlighting the food:

The third also pulls from Instagram but this time puts the focus on people and family (including the dog!):

Bookings.com 'Only 5 rooms left' prompt for urgency
We've recently done a little dive into whether landing pages convert better with images showing: A) the product; B) people; or C) people-with-the-product. The results are quite interesting, but that's for another day.
Which variant do you think will win?