Either the Chevrolet or the Ford is likely to be about average in reliability, with the record for the Ram is spottier. The 2015 Ford wasn't bad in our stats, but I would still wonder about it since it was the first model year of the new design. If you want an 8-foot bed extended cab half-ton truck, I think only Ford has offered this combination recently. With the others you'll need an HD pickup, which will be more expensive and less fuel efficient. The Ford 2.7T engine is probably the most efficient of those you're considering. I don't think the 3.5T is much more efficient than a GM V8, but it does have more low-end torque.
With any of the turbocharged engines there is more chance for reliability issues in the long-term.
Seat comfort is highly subjective. I'd try to spend enough time in each contender to evaluate it.