Believe the 2.7 EcoBoost is the best bang for the buck right now. Can be had for the same or cheaper than a Tacoma, depending on where you look.Look at the Ford F150 2.7l Ecoboost . The 2018 with 10 speed tranny gets ~ 2 mpg better than the 2017 6 speed. These trucks are super fun to drive and seem to be reliable after some teething issues with the early models. The gas milage is exceptional for a gas 1/2 ton pickup. 21/19/24 mpg.
Go to a dealer and take a test drive and you'll experience the lively almost sports car like performance. I own a 2018 3.5 EB but had the use of a 2017 2.7 EB for several months and I'd probably go for the 2.7 if gas milage is a concern. The 2.7 has plenty of high torque power for almost any situation. If you're coming from a Taco, there'll be a huge difference. If you need to tow heavy then the 3.5 is optimum. Really good payload too. Fully boxed frame.
Its' 325 HP/400TQ feel about right, not overkill and not wimpy either....it is the Goldilocks of power plants out there currently. I was talking to forum member pnut, he says he gets 22-23 mpg out of his. Which is basically what people doing the Cummins 2.8 swap are getting from my research.