recommend best way to move dirt around my valley

[crazyal]

I bought an old (75) international dump truck cheap for moving dirt. Since then scrap steel prices have gone up but you may be able to find an old Chevy or Ford, something larger than a 1 ton, for less than a grand. It doesn't have to be road worthy. Things like dry rot tires, rusty sheet metal, worn steering parts are not really a big deal when all you're doing is moving dirt around. The old Chevy and Ford trucks use standard v8 engine parts and most of the drive train is pretty rugged. About all you need are working brakes. Air brakes are pretty simple to work on. Just do a search on Craig's list to see what's around you.

 

[Arc weld]

You'd be surprised at what a rubber tired skid steer will do. You can put a set of chains on the rear tires if need be but for an overall machine, it's hard to beat a skid steer for versatility. If you have a long driveway get an angle blade to move snow. A dump truck would be OK but you don't want something you'll be constantly having to fix and if you have steep slopes, you're going to want something safe with good brakes etc. For 25K you could get a good steer and a good tractor with a 3 pt. hitch.

 

[Verticaltrx]

Get the largest skid steer you can afford. You'll want one with a long wheel base, plenty of hp and weight. You can then add a set of over-the-tire steel tracks if the situation warrants. The steel tracks will not only improve traction but also lower the center of gravity some.

 

[scoutcub]

I would offer that out of the 4 options you listed, the tracked skidsteer would be the best. And most versatile.
However, I would also consider a tracked loader, especially one with a 4 in 1 bucket.
And, the older dump truck would definitely be on the list.