A thin laminate. With the epoxy in place you cannot have anything other than a floating floor (or carpet). I would look at a decent laminate with 8mm thickness (no attached underlay...just bare).

Lay it over the concrete (you can get away with QuietWalk's 1.2mm underlay....it will be just fine) and enjoy.

I'm sorry you didn't love your concrete. Don't feel bad. Most people I have come across (like 75%-85%) who have had finished concrete floors do NOT like them. The average time it takes for a concrete floor to be 'covered up' = 7 years. This is normal. Do what you can with what is allowed over top.

If you ever want a permanent floor (like tiles or stone) you MUST grind off all the epoxy. Epoxy prevents things from being 'attached' the concrete. That's the biggest down side to finished concrete floors. Whatever money you had to pay to get them finished, is normally twice the amount you have to pay to get them 'unfinished'. A $7/sf epoxy finish turns into a $3/sf 'grinding' when you want to get rid of it.....that sort of thing.

Thank you, SJ. What are the relative advantages of laminate vs. carpet, in this case? The use of this basement area has evolved into two guest rooms, a workshop, and a largish office/media room. We usually walk around barefoot, so maybe carpet would be best, at least for everything except the workshop.

Carpet is always the least expensive and the fastest to install. Just make sure you work with a pad that will not melt (ie. is formulated for the hydronic heat = a little thinner).