On NBA 2K7, I have both of them on the Wizards. Two seasons into the Association, my front court is beast.
Anyways, I would take Andris Biedrins hands down. Lee has slightly better numbers at the moment, but Biedrins is a much better shotblocker plus he is only 21 years old. David Lee is 24 which isn't old but he has less time to turn into something really special. Its really hard to pick though, they are both solid players.
Biedrins is a better player because he has a more fluid offense and is significantly younger than David Lee. He is a center which means he is more valuable and he has better defensive instincts than Lee. Lee is more athletic but Biedrins has a higher ceiling.
Biedrins will command around 12 mil a year while Lee will probably ask for about 8. Biedrins may be the better player, but Lee is the better bargain.
Biedrins is better IMO because he has better defense and can grab boards just about as well. There offenses are about equal, maybe Lee with a slight advantage. Lee is more athletic but Biedrins is more valuable in the sense of his presense and ability and block and alter shots. Both have a bright future I do agree with most of you that Lee will be the better bargain in the future.