We tried the Mantis here in kentucky, a lot of clay in the soil when we first started gardening. The only thing it is good for is weeding after the hard work has been done. The Mantis makes a very narrow row and takes a long time to do that in hard soil.
We got a Troy Built, it makes a two foot wide row instead of 6 inches. It is very heavy. One nice thing about it is that it goes deep. To start a new plot it will take a few times through but once the ground is broken up the first time it goes right through it. I always make two passes one in slow speed and one in fast to break up any clods. When I get done my feet will sink in about 6 inches or so walking on the tilled soil. Plants come up from seeds quickly in the soft dirt.
Because a tiller is used so infrequently they will last forever. Buy a used one at a yard sale or on Craigs list.
My Troy built starts on the first pull every time.
I have two large plots. I like being able to till the ground in a matter of minutes instead of fighting for hours.
Good luck and happy gardening, home grown food is much better than the salty store bought junk.