You've got to decide what is important to you, 'cause you can't have it all.
First, you are going to lose fuel economy no matter what. Even replacing the OE tires with the same make and model means some loss in FE. And if you chose a good wearing tire, it's going to be even worse.
That's because worn tires have lower rolling resistance than full treaded ones (all other things being equal), And since there is a technology triangle involving treadwear, traction (especially wet traction), and rolling resistance, replacement tires are generally worse for FE, but better for wear and grip.