I wanted a tiller for years before I broke down and bought one. Simple logic convinced me I needed an expensive name brand model, and I just couldn't justify the expense.
I finally got the opportunity to try a 72" King Kutter about 5 years back. It took all of 10 minutes to convince me that it was as good as a tiller needs to be. And it was (is) the cheapest one I could get at that time.
So I bought one. Never second guessed that choice. I've used and abused it. Rocks, roots, a buried foundation, re-bar, fence wire, and every now and then, some dirt. Nothing shakes it. I bought 4 left and 4 right hand tines as spares when I got the tiller. I've used one of each so far. Changed oil a couple times, and kept the drive shaft greased.
I won't try to say there isn't a tiller made any better, just the King Kutter is as good as it needs to be.