Depends on your needs. A rear tine is IMHO easier to handle as long as the garden is large enough to warrant it. The tines turn much faster and do a better job of cultivating. The downsides are weight and reduced maneuverability in tight areas.
The front tine is much more compact and better suited to smaller gardens. It is harder to handle and will beat up the operator in hard packed soil. I was not long learning why dad handed it to me once I got old enough.

There is not a "one size fits all" answer to your question. Canguy makes a good point. Depends on a number of things. How big is your plot, what type soil, what you're going to use it for ... not to mention how much money you're going to spend. I have a large rear-tine unit that I use for breaking new ground, as well as my first & last tilling of the season. For the tilling at planting time and for cultivating I use a small front-tine unit. I actually use the small tiller the most. Knowing what I do now, if I were starting out I would rent a big rear-tine machine for infrequent needs, and buy a small machine.

Dale,

"What works more efficiently, a front or rear tine tiller?"

I prefer and use a mid-tined tiller. Specifically, a Merry Tiller International Model. The International Model costs considerably less with a Briggs & Stratton engine, which also performs very well, and the B&S version has the advantage of an on-the-handle throttle control.

MM