"I like epimedium but it doesn't spread much.." There are hundreds of cultivars of epimediums and many species. Some are clumpers, others slow spreaders. I have quite a large area of one of the yellow flowered spreaders--semi-evergreen. Lily of the valley is so invasive I'd be reluctant to plant it in a container. As for Liriope, only L. spicata is going to spread. L. muscari is a clumper. Latin names are quite important in getting what you want.

I love my periwinkle!! Yes it is aggressive but I have not found that it chokes out any of the larger perennials that it shares space with. I do pull gallons of it each spring to keep it away from the hosta and astilbe, but still I do not think it would choke them out. I am struggling to remove the pachysandra. It comes up from the tiniest root, like Lily of the Valley. Lily of the valley has been the toughest to eradicate. Its web of roots is near impossible to cut through with a spade. Be VERY careful where you plant that. The blooms smell HEAVENLY and I grow it for that but it has its down side. Ajuga is also very invasive given time but easily torn from where you don't want it. Not sure if this includes the grass..I have some that gets a squirt of weed killer when I make my rounds....

Offer your liriope to folks on hillside gardening.

I don't know what kind of liriope you had experience with but mine doesn't spread at all. It's interesting that you put sweet woodruff on the list of plants you like but that spreads aggressively. Whoever owns the garden pictured above has done a great job.

In addition to battling with Lily of the Valley and Sweet Woodruff for twenty years, my two biggest thugs are Spanish bluebells (Hyacinthoides hispanica) and Grape Hyacinth (Muscari armeniacum) Both have pretty blue flowers but seed freely in shade and sun and smother more desirable plants with their foliage. I've been trying to eradicate them too for twenty years. These thugs are all interwoven with shrubs, ferns and perennials in my shade bed and it has been impossible to get rid of them.

Just a few comments.

I hate vinca minor with a passion, absolutely impossible to like. Not dense enough to make a really good cover and impossible to keep in bounds.

Pachysandra kills out everything in its path. My wife loves it and I cringe at the sight of it.

Many epimediums form lovely ground cover. My favorites are E, x 'Frohenleiten' and E. koreanum, although E. alpinum and E. pinnatum sp. colchicum are nice also.