I have kind of thing about garden edging. Some might say an obsession. I hate a messy edge. My garden boy has a good system down with the shovel after all these years, of digging the edge. He does it in the spring and then maybe once or twice over the growing season. Here he is doing a fall edging. He uses a square spade and goes down vertically with the spade about 2 inches and then pulls the handle towards him and pushed the dirt forward. I think it looks pretty good.
Around my front perennial garden I mostly use a rock edging. What I really like is stacked stone, someday that's what I'll have around my garden.
And of course I love this slate edging (at Chanticleer). I notice a lot of public gardens have this type of edging.