I actually think Chandler is a slightly better player on both ends of the court, however, we all know that Chandlers problem is staying healthy.
Well to use a bit of statistical analysis, Haywood has posted PER's of 16.1, 14.9 (he missed most of the year), and 18.3 over the past three years. Over his career he's averaged 11.3 points, 9.3 rebounds, and 2.2 blocks per 36 min. Chandler has posted PER's of 12.5, 13.4, and 17.5 over the past three years and averages 10.5 points, 11.5 rebounds, and 2.1 blocks per 36 min in his career.
The differences are fairly marginal until you see that Chandler has missed significant chunks of the past two years while making around twice as much as Haywood has. Nazr actually showed some life as an off-the-bench scorer down low last season, so ideally (for me at least) we'd be able to dump Chandler's contract and pick up Haywood, which would leave some payroll still open to make some other moves.