Edge of Sanity's claim to fame was being a 'progressive death metal band', and as such the entire band really became obsolete as soon as Moontower hit the racks.
But for me, Spectral Sorrows (Sacrificed and the Manowar cover Blood of My Enemies are my favorites), Purgatory Afterglow (the whole album as long as I don't read any lyrics), and Crimson (which song here, hmm, hard decision) are the ones to have (although I have them all...), but Dan Swanö himself loves Unorthodox best.
Sacrificed, Blood of My Enemies, Black Tears (Purgatory Afterglow) and Losing Myself (Infernal) are all great tracks, but not really representative of Edge of Sanity overall, IMO.
Purgatory Afterglow kicks ass, Infernal is really good too, I wouldn't recommend Crimson to a first time listener...don't forget the Until Eternity Ends ep either.