I've used RefMan and Endnote. I have to say I like RefMan much better. I find Endnote overly simplistic and certain key features are not present in Endnote. However, entering authors is FAR easier in Endnote than RefMan. Unfortunately RefMan isn't updated all too often as Endnote is more popular primarily because it's marketed to undergrads as well
"Some men see things as they are and say why, I dream things that never were and say why not"
"If you think research is expensive, try disease." - Mary Lasker