Q.Is creeping thyme easy to control
I need a durable yet non-aggressive ground cover for small plot between the sidewalk and road. Having battled apple mint, which spread UNDER the sidewalk to this area, I’m concerned about something which will stay put, yet grow well. After pulling a lot of mint out by the roots, and chopping down the remainder of the mint and weeds, I plan to rent a tiller and then try to get the rest of the roots, and plant something attractive (which, I hope, will not be overcome by any mint remnants). I’m thinking that perhaps creeping thyme would work well. I’m also considering elfin thyme, creeping phlox, or purple shamrock. Any advice would be greatly appreciated.
First I would use caution in 'tilling' the area with the mint. This can send hundreds of root sections into the soil. You may have even more mint then you began with.
Here is a link that has a few suggestions for mint control.
https://www.gardeningknowhow.com/edible/herbs/mint/invasive-mint-how-to-kill-mint-plants.htm
I also have links for the ground covers you mention.
I have Creeping Thyme in a walkway and do not find it invasive. It has spread slowly and is very easy to remove a piece and replant in another location to continue fill in gaps.
https://www.gardeningknowhow.com/edible/herbs/thyme/growing-creeping-thyme.htm
https://www.gardeningknowhow.com/ornamental/groundcover/creeping-phlox/creeping-phlox-planting.htm
https://www.gardeningknowhow.com/ornamental/groundcover/