That 2018 F150 w/ the 3.3L and 6AT sounds like a solid choice!
If I remember right with my 2017 Ram 1500 QC 4x4 pentastar, 3.21 gears, with my driving, It would only go into 8th if I was dead steady at highway speeds. It would spend a long time in 7th and the only you'd know is if you were a car person, or really paying attention. My 2019 Ram 1500 CC, 4x4, hemi, 3.21, it's ZF8 was a bit busier, but still super nice. MDS is the most annoying thing with the hemi, but I'd keep that off by manually selecting 8th any time it annoyed me.
Regardless, the Stellantis version of the ZF8 coupled to the 3.6L and the "real" ZF8 in the hemi were definitely my all time favorite AT in anything I've owned.