The Craftsman models 120 and 208 are both excellent choices for small tillers according to the website Top Ten Reviews. The Club Cadet models FT24 and RT also get good reviews.
The Craftsman 120 is a 120-volt mini tiller with good maneuverability. It does have a cord, though, so the range is somewhat limited. The Craftsman 208 is a good choice for a durable and worry-free gas tiller.
The Club Cadet FT24 features adjustable width and depth along with a variety of other useful features. The Club Cadet FT can handle larger areas than the other tillers listed here, but it isn't as easy to maneuver.