For everyday driving I'd choose neither if that's an option.
Is it an option? If I were to drive somewhere and lose or break my phone would I be unable to drive home? What about letting someone else borrow my Slate Truck? Would they need to install an app, or would they need to borrow my phone...
I'm inclined to take a less-is-more approach: Off-road Tires + Lift, Fender Flares, Blacktop cab wrap, Front Light Upgrade.
If a well-designed lockable bed cover (tonneau) were available I'd opt for that as well.
Door Cubbies and Rubber Floor Liner would add some interior practicality.