Ardour is excellent, now of quite professional quality, and free, but only runs on Linux.
Reaper comes highly recommended (by others, I've never used it) for Windows. Not free, but you get a free demo (fully functional, time limited 60 days) and it's not expensive to buy if you want to keep using it. ($60 for non-commercial individual use or very small business)
Both are designed as multitrack mixers, but they'll be far better than Audacity for editing simple stereo recordings.

Harrison Mixbus is a way of getting a version of Ardour for Windows, but not so cheap.

I wouldn't say any of them is simple to use. They are necessarily complicated packages because they are designed to tackle a wide range of tasks.