Go with a diesel, we've used them for years on the farm and as daily drivers.
I've owned the Ford,Dodge and Chevy. The 7.3 was an outstanding motor, I run one to almost 300k before selling it with no issues. I was given a 2005 crew cab 3/4 ton Ford lariat 4x4 for a sales bonus, it had the 6.0 diesel, what a piece of crap, got rid of it with 40k miles, the only thing good about it was it didn't cost me a penny, great truck horrible motor. My favorite out of the bunch is the Chevy Duramax with the Allison behind it, fantastic mileage great tranny, quiet no issues. Our wood truck is a Dodge 2500 4x4 with the Cummins, gave 1500.00 for it as it was a bank repo, interior was ROUGH, it had around 180k on it when we got it, the Cummins has been flawless, the only problem is that it is a Cummins with a Dodge wrapped around it.
Don't be afraid of a diesel, the key is like anything else preventive maint., clean fuel, change fuel filters every 15 to 20k miles, we change our oil in ours every 10k miles, using Rotella 15-40. My BIL has over 375k on a 7.3, an uncle has run a Cummins up over 350k in an old 94 Dodge 3/4 ton truck, after you use them as farm for a while as a feed truck they usually get so beat up and broke down from hauling two big round bales at a time that after a few years they won't give nothing for trade, it's just cheaper to run them until they die.
Stay away from the Dodge diesel auto trannies.....weak. Also stay away from the 6.5 chevy diesel, anything after I believe 2001 had the Duramax. The Duramax was/is an isuzu design, the Ford 7.3 was an International design.
Don't be afraid to go with a diesel, see if they will let you take it to a shop and have a scan run on it, the scan will tell if it has any issues/injector/pump etc. around here a scan only runs 40.00 bucks, cheap when your dropping that kind of coin.