Well the EQ on cowon was one thing I loved (also speeding up playback speed was awesome for music, and helpful for videos when i'm watching my videos in 1.5x). I also just liked the navigation of the music "app" on the cowon d2. It was simple, skinable, and most importantly I could pick a different song by browsing the directories and it would still random to a song of a different directory. The SGS is a nice device but if cowon came out with a phone I would expect the quality of the audio side of things to be amazing.
(I'm waiting to test the sgs music app on my nexus one when someone ports it over, it looks decent and I hate pretty much all music players i've come across on android - sadly, they suck.)