If it's the Aeroworks Edge 60/90, I'd say YS120. I've flown them with a OS .91FX 2-stroke, and also with a YS.91 4-stroke. Of these the one with YS performed very well, although it might could use a little bit morel. The one with the OS definately needed more though.
I think one of these with a YS 120 would be radical.

Some of it might depend on your experience level too. If your wanting all out unlimited(YS120), or a good aerobatic plane that you can grow with go with a smaller 2-stroke.

Although a 61FX would fly the plane, I think it merits more engine then that.

This was my experience with the plane, as I've been a test pilot of 2 of these so far, and had opportunity to shake them out a bit.
An owner might have a different opinion though. I hope this helps.