Wood is just to bulky and heavy IMHO. Also too limited, since they will only raise it up as much as you made.
I've tried a few different brands and found there to be the strongest and flexible. Have used them in sand, asphalt, gravel and if they bend they retake their original shape. They are also easier to store, and lighter. My unit weighs in at +/-13,000
total and lifts it fine.
Even though I now have the Hydraulic Bigfoot Leveling system, I keep 2 sets on hand.