Get the biggest one you can afford.
I would stick with Brand Names.
We have a small 5HP that is mostly worthless when it comes to actually chipping wood,
but it does wonders turning leaves, weeds, paper, and cardboard into shredded layers for the Compost bins.
We have raised beds in our Veggie Garden, and we put our beds to sleep for the Winter
by stretching a tarp over the raised bed,
screwing it down on the corners with a screw gun,
rolling up the "wood chipper" and sticking the outlet under the tarp,
and then dumping old grass clippings and leaves into the hopper,
and taking the tarp off when full.
Its EZ, fast, works well,
and leaves an excellent layer of shredded compost/mulch over the bed until its time to plant again.
...but like I said, 5HP won't really chip any wood unless you have a LOT of time & patience.
If you are planning of chipping anything with a bigger circumference than a broom stick,
10HP is the minimum I wold look for.
YMMV.
ALWAYS wear gloves and safety glasses.
NO loose clothing, dangling belts or straps,
or anything that can get caught in the machinery.
Happy Chipping!
It IS fun to grind up an ugly pile of stuff.
Real Power Trip.
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