If you are starting a garden in an area without any grass, an edger is a minor luxury. If you have sod, however, there is no better way than an edger to break it up so you can turn it over or remove it. Unless you have tall weeds, or no grass, this is the first tool you will want when starting a garden.
The first thing you need to choose for an edger is what kind of head you want. The classical lawn edger has a half-moon shape: The rounded edges make it easier to push the edger into the sod, and the solid blade makes it easier to lift the sod up. This is good for cutting out small individual blocks in heavy clay soil. If you have a large area you want to cut up, you may want to opt for a rotary blade: This will cut the sod very quickly, especially if you get a powered model, but you will need a different tool to pick it up. A third option is a square blade: This works best on either light, sandy soil, or sod that has been previously cut. A bonus of this style is that it can also be used for chopping ice in the winter. In areas with lots of roots, you may want to get a head that has a saw-tooth edge:
The next thing to pay attention to is how the top of the blade and how it connects to the handle. If you look closely at the first and fourth examples, you will see little flanges on either side of the hand that facilitate using your foot to push the edger into the soil. If you really want to take advantage of this feature, getting one with a split handle will allow you to put your foot right in the center: Without a flange, the ice chopper is very awkward to use your foot on, and the rotary edger cannot take much downward pressure at all.
The third consideration is the material the handle is made of. Most are made of steel, sometimes stainless; a few like the second and third examples have wooden handles. Fiberglass is another possibility but it is very rare.
The final two options for the handle are linked: whether to have a long or short handle, and whether to have a T handle at the top or not. As you can see in the second and third examples, long handle are usually straight. Short handles usually have T handles, as in the first and fifth examples, but occasionally you will find an O handle like the fourth example.
As an Amazon Associate I earn from qualifying purchases. The products listed are meant to exemplify the variety of choices you have in choosing a lawn edger. Listing does not constitute an endorsement as I do not have any experience using these particular models.