Size is probably the single biggest choice, for me, in what I will choose for a tiller. As a person with an upper limb disability, I have to know that I can handle the machine. When we purchased our Huskee Viper, size mattered. It is small for the area we are tilling, but it is manageable for my limited mobility. The one downside to it, is it is hard to pull the cord to start, without someone else holding it so it doesn't tip over. You can get the option of an electric start, and I wish I had. It would have made it much easier. I thought about purchasing a rear tine tiller, but didn't think I could handle the power of it.
The price range on tillers can run from just a few hundred dollars to several thousands of dollars. Budgeting for this is a must. You must also plan on gas, oil, and repairs if needed. Tillers take a beating, and many times will need servicing at least once per year.
What size area are you planning to work with the tiller? Obviously, for the small urban homesteader, a smaller tiller will probably do the job. If you are working a larger area, a larger and more powerful tiller will be in order. We went with the smaller tiller, because we were able last year, to have a gentleman with a large tractor come and break up what was once pasture, for our garden area. So working with the smaller tiller for just the rows we want to work, makes sense. He did the bulk of the hard work for us with the prep work. It was worth the $100 we paid, and I will probably have him come again this fall to expand our area.
Now, for my specific thoughts on the tiller we have. It's my best friend in the garden :) I can accomplish a lot with this, in 1/4 the time of doing it by hand. I use it in between my rows during the growing season to do a light tilling of just the top surface of the soil to help break up and get weeds out. I will usually run the tiller lightly over the top with 2 passes, then I can go along with my rake and pull the weeds out.
It is a small tiller, but I am impressed with the power it has. Even with our never ending crabgrass and wiregrass, it chops right through it. The bad thing is that grass tends to wind around the tines, so stopping ocassionally to clean it up is necessary. But it's a small price to pay. It is very good on gas/oil. I can usually work several hours with it at full throttle, before I have to refill.
I highly recommend this tiller, especially for those of you with small gardens to work. Down the road will will be saving for something that is easy for me to operate alone, and will cover more area. The option I have found is the Roto-Hog pull behind tiller. I like the quality of DR products as my parents have owned several, and it is a wider version. Most are only 24" wide, while this one is 36", and has 12 full tines. With it being gas powered, it works separately from the mower, and no pto or other power options are necessary. However, it is not cheap. It will require most of this coming winter to save up for it, so that we will have it for next year's planting. But in the long run it will be worth it.
Disclaimer: I receive no compensation for the mention of these products in this post. It is based solely on my own experience and/or research.