How does Priceline (Hotwire etc) decide your hotel?

Working at a hotel I understand the hotels’ side. We simply set a price and if Hotwire or Priceline has a bid that meets that they give it to us (yes I know Hotwire doesn’t bid)

Let’s say Marriott says 69.00 is Ok. Westin says 70.00 is OK. Hilton says 69.00 is OK and Wyndham has 70.00 is OK.

Now I bid 69.00 now Westin and Wyndham are out. But Hilton and Marriott both come across as OK. How does Priceline put me in the hotel. How do they decide between Hilton and Marriott?