We have virtually no reliability information on the Titan. During its first few model years it had a poor reliability reputation, but Nissan likely improved the truck in following model years.
In terms of consistent reliability, I'd rank the others Toyota, GM, Ram, Ford. None has been awful, but the Ford has been least consistently reliable.
Also, given problems with aluminum hoods on multiple Ford models in the past decade I'm concerned about the aluminum body on the 2015 and up F-150. It might be fine, but it could also end up being a disaster for Ford and for truck owners (Ford tends to dodge responsibility for its engineering mistakes).
I do agree that the Ford would be best for fuel economy, while the Ram, Titan, and Tundra are all relatively thirsty. The latest GM V8s are the most efficient V8s. Though their EPA ratings are a few mpg short of the Ford 2.7T, some reviewers suggest that their real-world fuel economy doesn't differ as much.
Overall, then, it seems to me that the Tundra is best for reliability, and the Ford is best for fuel economy, but the GM trucks could offer the best combination of reliability and fuel economy.