This is the only attempt I've seen at someone quantifying how magnets sound. I'm sure if you showed this to enough people you could start a lot of arguments. It is nice they he tried to quantify it though.
Here's the caption to this picture.
Here is a handy chart that gives a general magnet tonality. Keep in mind that tone is derived from the sum of all aspects of the pickup. The d.c. resistance, quality of the parts, and builders skill also affect how a pickup sounds. The magnet sculpts the end result.