I love that show. It's got a lot of amazing characters, like Greene, Ross, Hathaway, Carter, Lewis, Benton, Abby, Luka, Corday and Romano (a character you love to hate). I think my favorite on-screen couples are Doug & Carol and Luka & Abby. What I also love ER is that it's intensity and most of it's complex stories on each episode that aired. It was too bad it got cancelled, but it's got all sorts of records and awards that we're well deserved.
Grey's Anatomy can never compare with ER because I don't like Grey's because it doesn't have the feel to it that ER had in the past. Grey's Anatomy is too much of a soap opera (no offense to the fans of Grey's Anatomy).
ER is the best medical drama in the world. A true legend.