"Do you prefer Starbucks or Peet's Coffee?" implies the following: "Do you prefer Starbucks' [coffee] or Peet's Coffee?" From what I've learned, this title is grammatically correct.
One should not joke about serious matters such as coffee. I meant what I said. Starbucks makes black, coffee-smelling crud and really tasty caffeinated-crud-added super-sugary high-fat drinks.
Correction: Starbucks "coffee" isn't coffee.