Which is truly the Best Spark Plug For a 2nd Gen 2007 Explorer Sport Trac 4.0 V6?

[DILLARD000]

Yep, fix the known problem with the OxSensor first, before spending money+time on other unknowns.
Bosch 15719 with 24i00 0m610 Long Cable+Plug is good to replace any Ford 4WireNarrowBand Sensor; allows routing the cable well away from any hot\moving parts, then just neatly CableTie up any extra slack.

 

[swshawaii]

^ aka Motorcraft SP412

Definitely the OE replacement for your 2008 V6. Appears Motorcraft doesn't have a direct replacement other than nickel. Autolite has Double Platinum APP5143 and Iridium XP5143.

More Information for MOTORCRAFT SP412

VERY important to check the .054" gap out of the box. Many manufacturers say pre-gapped from the factory, but all it takes is a short drop on the snout, and the center electrode closes.
Also, NGK says anti seize is not needed on their plated plugs. Others say anti seize alters torque and good grounding. Regardless of spark plug plating, I would never consider installing spark plugs in aluminum heads without a light coat of copper or nickel anti seize, especially at these 85K+ intervals. YMMV

 

[bk10s]

O-E-M