Well, when you go to buy, make sure to get a diesel and not a deisel.
If you have a diesel tank on the property to fill up at, a diesel is a no brainer IMO. If you have to haul gas, it is a tossup.
Drive them both and buy what you like. I wish the three Honda 4 wheelers we have were diesel to make fillups easier. Pulling up the diesel mower w kubota engine to the bulk tank sure spoils me. Not sure how the engines hold up in Rangers for you though.
Analyze how much you will use it and how often it will sit up if gas. If you are hauling it around, you might consider matching it to whatever your truck burns.