Regardless of the plug design, you'll find that your 5.4L will perform the best with the Motorcraft plugs in it.
The F150 guys that have put in Champion and other brands have found that after a few thousand miles they are having sputtering and hesitation issues, amongst other things.
I, and a lot of the truck guys, will recommend you stick with the Motorcraft plugs. You shouldn't have too much of a problem with an 07+ Expy as Ford had pretty much caught on by then and made a fix. You're not likely to break of 6-8 of them like the 04-06 F150 guys.