What size branches will you realistically be regularly chipping? That's the key to determining the size of wood chipper you need, there's not much point getting a chipper that can chop up 50mm branches if you'll only chop a few up every other year or something. I picked up a Bosch AXT Rapid 2200 for £50 off Marktplace, realisitcally they're such simple machines so not much to go wrong and the blades can easilty be sharpened/reversed/replaced it seemed potty to buy a brand new one. But it maxes out at about 30mm, anything bigger I just cut it into manageable lengths but 99% its less than that but then we also have a garden waste collection service down here.