I'll start off by saying I'm a Ford Powestroke and Cummins certified tech and I work on diesel trucks every day. I drive an F150.
Don't by a diesel unless you have the tools, knowledge, time and space to work on it or you have the money and secondary vehicle to have it at the shop every now and then.
My 2004 F150 5.4 4x4 has a GVW around 7200lbs, not bad. It also rides like a car compared to a Superduty. I just hit 100k, in the past 60k I have put in 2 struts (quick lifts) and 2 shocks, throttle body, serp belt, brakes and tires. Thats it.
No high pressure oil issues, head gaskets, egr coolers, oil coolers, cam sensors, etc (6.0), no high pressure fuel pump, regen, radiators, thermostats, etc, etc, etc (6.4), no DEF, brakes at 30k, exhaust temp sensors, plastic fuel filter housings (6.7). Not to mention the $9,000 option to buy a diesel these days.
My next truck will be an ecoboost 150 or a raptor. My next company work truck will be another F550 7.3 4x4
If you're not working it regularly, skip the superduty unless you "need" to have solid axles, want to plow commercially or will be towing/hauling ALOT.
If you really want a superduty, I'd recommend a 5.4 if you're not going to work the truck and 6.8 if you're plowing, towing and hauling. Otherwise, get a newer 6.2 and you'll have the best of both worlds.
If you're set on a diesel, get a 7.3. Worst case a 6.0 or even a new 6.7 if its under warranty. Avoid the 6.4 like the plague.
If you have any questions about these trucks, don't hesitate to pm or email me.
Sorry about the rant...
Mike
SummitFleetServices@Yahoo.com