And the disclaimer to the meme: it’s worth pointing out that Soylent Drink gets about 2.5% of its calories from added sugar while Ensure Original gets 27% of its calories from added sugars.
Milk is a common allergen, especially among young children, but Soylent is also made with common food allergens (notably, soy protein and gluten), so on balance that issue is kind of a wash (or, maybe, advantage to Ensure), though specific users may avoid one or the other based on their specific allergies and conditions.