Is using that ox that pulls the plow a little out of date? Worse yet do you have to try and break the soil yourself every spring? In either case you would probably be in the market to rent or purchase a rototiller.
If you have a smaller garden or you only use it once a year, renting a rototiller would probably be your safest bet. However, if you plan on using it multiple times a year, using it year after year, or you have a large garden you may look at purchasing one a bit more strongly.
When renting or looking to own a rototiller, there are a couple different types to look at. For people with small home gardens, a front tine tiller would work well for you. Front tine tillers have diggers that will propel forward and may take multiple passes.
For a larger garden, you might want to look at a rear tine tiller. It is called this because the diggers rotate backwards, making them easier to propel and are great when it comes to going through thicker soil.
Other features that you should think about when buying is the amount of horsepower and what kind of depth the machine will give you when digging into the ground. A salesman at the store should also be able to give you warranty information.
Good luck hunting for the rototiller that you are looking to rent or own. Either way you will get a workout on the way to a great looking garden.