What is the best plane for use on a large ranch.?

Cessna 185. With all seats removed, you can haul enough fence material to build a ¼ mile of fence, or haul a few bales of hay to a downed animal.

I don't think you will find any aircraft cheap at this time.

Edit: I would stick with an all aluminum airframe. If your landing area is not completely free of brush and sticks, you will spend valuable time patching the fabric on a rag and tube airframe.

Well cowboy I would say the best bang for the buck is a Stinson 108 Station Wagon. A well kept secret. Manufacturing stopped long ago but used and good ones are still available, some with high horsepower engine upgrades. REAL PERFORMERS. Look on barnstormers.com.

Believe it or not a Stinson 108 can work well in this application. Can be had with a Lycoming conversion for half the price of a 180.

A piper super cub only has two seats but you can land on anything, you could get it to land in less than 100 feet, they are tough and not too expensive, but for 4 seats, you should look into a cessna 180, it can land very short and has four seats

Go with the Cessna 180 or 185, that's your best bet. Be prepared to pay $100K for a good one.

Cessna 170 or 180. The 180 would be better if you really need to carry four people.

The ZENAIR "CH" series of aircraft are excellent for this application. Good payload and STOL capability. A very robust plane.

http://www.zenair.com/