I've never noticed any turbo lag with my Ecoboost, honestly pulled down low better than my Hemi, which feels laggy in comparison.
That being said, I really rather have the Hemi do to the overall character and sound the V8 has. With an aftermarket exhaust, my Rebel has a sense of occasion when driving that cannot be replicated by any V6.
It's kinda childish I know, but it's a big part of the appeal of these trucks. However, based on the latest comparison test, the Hemi is the slowest of the current crop of full size trucks, so more drivetrain options are welcomed for this platform to keep it competitive.