For anyone who isn't a single issue voter, there is much to choose between them.
There are plenty of things that Lieberman is conservative on -- he's a war hawk (which is bad enough), has a mediocre record on civil liberties.
BUT, he's no Zell Miller, not by a long shot. Lieberman has an excellent record on reproductive rights, an excellent record on the environment, an excellent record on labor issues and a long history of standing up for African American civil rights.
To put it all in perspective, last year, Joe Lieberman voted the way the Christian Coalition wanted him to vote 0% of the time and Zell Miller voted the way they wanted him to vote 100% of the time. Here are some more ratings of his voting record from project vote smart.
http://www.vote-smart.org/issue_rating_category.php?can_id=S01411032003 On the votes that the National Abortion Reproductive Rights Action League considered to be the most important in 2003, Senator Lieberman voted their preferred position 100 percent of the time. (Zell's rating was 0)
2003 Based on the votes, and co-sponsorship of legislation the The Humane Society of the United States considered to be the most important in 2003, Senator Lieberman voted their preferred position 100 percent of the time. (Zell's rating was 0)
2000 On the votes that the Americans for the Arts considered to be the most important in 2000, Senator Lieberman voted their preferred position 100 percent of the time. (Zell didn't have a rating)
2003 On the votes that the Americans for Tax Reform considered to be the most important in 2003, Senator Lieberman voted their preferred position 5 percent of the time. (Zell's rating was 70)
2001-2002 On the votes that the American Civil Liberties Union considered to be the most important in 2001-2002 , Senator Lieberman voted their preferred position 40 percent of the time. (like I said, mediocre, but Zell's rating was 25)
2001-2002 On the votes that the National Association for the Advancement of Colored People considered to be the most important in 2001-2002, Senator Lieberman voted their preferred position 94 percent of the time. (Zell's rating was 15)
2003 On the votes that the Christian Coalition considered to be the most important in 2003 , Senator Lieberman voted their preferred position 0 percent of the time. (Zell's rating was 100)
2003 On the votes that the National Education Association considered to be the most important in 2003, Senator Lieberman voted their preferred position 86 percent of the time (was 100% the year before; Zell's rating was 25).
2003 On the votes that the Sierra Club considered to be the most important in 2003, Senator Lieberman voted their preferred position 100 percent of the time (Zell's rating was 0).
2003 On the votes that the Family Research Council considered to be the most important in 2003, Senator Lieberman voted their preferred position 0 percent of the time. (Zell's rating was 86)
2003 On the votes that the Brady Campaign to Prevent Gun Violence considered to be the most important as of 2003, Senator Lieberman voted their preferred position 90 percent of the time. (Zell's rating was 50)
2003 On the votes that the American Public Health Association considered to be the most important in 2003, Senator Lieberman voted their preferred position 100 percent of the time. (Zell's rating was 0)
2003 On the votes that the AFL-CIO considered to be the most important in 2003, Senator Lieberman voted their preferred position 100 percent of the time (Zell's rating was 8).
2003 On the votes that the Alliance for Retired Americans considered to be the most important in 2003, Senator Lieberman voted their preferred position 100 percent of the time. (Zell's rating was 0)