I'd put money on the fact that in the first 5 years of ownership, the money you spend repairing any of the new diesels on your list will be enough to buy your current F350, and who ever buys that F350 from you will still be running it up and down the road without a care in the world. If the body is in decent shape, I'd drive what you have until you can't. Not sure if you've done any mods to it, but I put a 7 position switch in mine and run it on the lowest setting and it drives a LOT better than it did stock. I've pulled an 8500 lb camper through TN with it, and it did fine. Going up the hills, I wasn't able to run 70mph, but I was able to outpace most of the semi traffic, and that was before I put the chip in it. If you haven't replaced the high pressure oil lines in it yet, go ahead and do that. They are a common failure point. Other that, keep a CPS sensor in your glove box, and maybe get the turbo rebuilt. As far as engine durability and longevity, I'd take your 7.3 over anything made post 2007 including everything on your list. Heck, I'd rebuild that 7.3 before I wasted my money on anything newer. Now, if your body is falling apart (like mine), and the the undercarriage is getting to the point that you're starting to question how long the frame is going to be able to hold up to to that 10k trailer, that's a different story. If I was in that boat, I'd start looking for another 7.3 out in Colorado, Wyoming, or the Dakotas, but that's just me.
If I absolutely HAD to have a newer truck, I'd be looking at a gas engine over a diesel, especially if I was only going to drive it a few times per year. For almost 20 years now, new diesel trucks really only make sense when you're towing heavy loads on a regular basis. Its not that every truck has major issues. Some never have any issues, but the odds are high, and there doesn't seem to be any in-betweens. People who run diesels tend to keep the ones that aren't broken which makes the used market a lot more risky than it used to be.
If I absolutely had to choose from one of the trucks on your list, I'd go with the Ram that has 300k on the clock, and I'd choose it specifically because the PO drove it enough to put 300k on it without giving up on it. I haven't stayed up on the Cummins engine, but last I checked they were still using the same block that they used in the 6BT (5.9), and Cummins offered to warrantee that engine for 500k when dodge started putting them in the Ram. Things have obviously changed since then and the EPA has royally effed up the diesel market, but the heart of the Cummins engine is still the most robust design on the market. I once asked one of their engineers why they ran so long. He said it was because Ford and Chevy use engines designed for 3/4 and 1 ton trucks meaning where as the 6BT was designed for industrial and agricultural industry where engines are normally run at wide open throttle for the entire duration of their lives, and in some of those applications you start the engine on day 1, and only shut it off to service it. Buying a diesel truck that's only a year or two old and has around 60k on the clock BEGS the question of why the PO isn't still driving it. Think about what they paid for those trucks new, and what they likely got on trade (or are trying to sell for now) and ask yourself why a person would take that big of a loss. The most likely and logical answer is that the trucks were money pits.
Just my 2 bits,
Mark