I don't have experience with the 7.4 or 6.0, but my 200K+ miles 6.4 in a '08 F250 still runs well. A couple of considerations (and Powerstroke overlanders, please speak up, I'm curious if it's just me):
If my Powerstroke runs dry (I know, don't do that, but I cracked the plastic pickup in the tank), it took a mechanic to reprime (pull the high-pressure lines to bleed)...I couldn't just add a can of diesel and fire it right up. I had a mechanically injected Magirus Duetz that had to be hand primed (basically an hour of steel masturbation) but I don't think modern diesel engines have that.
Maintenance is EXPENSIVE! As mentioned earlier, there is 16 quarts of oil, fuel filters, but also turbos are pricey AF and it may be easier on the older 6.0 and 7.4, but on my '08 6.4, you have to raise the cab to replace the turbo...that's ridiculously costly. You are not changing a high-pressure fuel pump in an afternoon in the parking lot of a Motel 6.
IMHO if you aren't going to do a lot of international travel (read questionable non-diesel fuel quality), for overlanding the gas option might be better.