Well if you use metal you'll have to pull that out if you want to make a change also. So best to lay out a bed design that can be retained and then edge it with something substantial. And lasting. The broad extruded concrete bands that certain contractors offer looks to be tops - serving as both a barrier to the lawn and as a pathway - but it is of course not cheap to have this done.

i never liked the metal ... perhaps it seemed un-natural to my eye ... though just a tiny bit better than plastic edging.. omg... kill me now.. lol ...

but disabuse yourself of the thought.. that it will be any more maintenance free than any other option .... grass can grow under anything .... and continue on the other side ...

gorgeous edging is gods work.. not easy .. and not fun ... but done right its sublime ...

and there is no fool proof no maintenance option.. imo ... and be aware of marketing mumbo jumbo that claims otherwise ...

my best idea... do one bed each of each option.. then observe for a year or two.. and then change them all to the best for you ..

ken

maybe you can get some ideas here: https://duckduckgo.com/?t=ffnt&q=garden+edging&iax=images&ia=images

I have metal edging that is unpainted. It is really thick and rusted right away. I knew it would do this. It really blends right in with the mulch, and I don't have to worry about damaging it with the weedeater. I did recently enlarge a bed. It was super easy to pull it up and move it.

Metal edging is way easier to move or remove if the need arises. Extruded concrete edging is expensive to install and equally expensive to remove......it is intended to be permanent.

The alternative is using purpose-made stone cobbles or bricks like this:

Garden Bed Edging Choices

If the flower bed is in lawn there will always be work to maintain the edge, unless you can lay a fairly wide flat mowing strip which the wheels of the mower can run along. Note Cooper’s reference to weedeating with a metal edging. The cobbles in the above pic work well with a hard surface but with lawn I’m pretty sure grass would still need to be trimmed back and would grow between the stones. I honestly like a traditional cut edge and I’ve not come across the idea of recutting it annually. I don’t think that’s necessary if the edge is sharply cut and you maintain it with edging shears or a mechanical edger.

Good point above! I have Bermuda grass and I need a barrier to slow it down from getting in the beds. I would love to have no edging. I almost didn't buy this house because of the grass type.

Inherited metal edging from previous owner. I imagine that it looked nice at some point and still does in some places. But in others it is completely buried by dirt and or grass. point being, you still have to maintain the border. I keep finding more buried edging the more I look. Lol.

depends on the look You want. Stone/pavers edging looks very formal and manicured. The border (when maintained) looks more natural to me.