Proposal: Implement the HWB colour model
Why:
It's easier to understand than HSL or HSV
It is simple and intuitive in use (see CSS4 page below)
It has less problems, such as 'extrema' issues (see Alvy paper below, and black issue here)
It is easy to calculate
It is a standard in CSS4
How:
Preferred: as parallel to other colour models, HSL, CMYK, etc
Alternative: just as extra option in HSL control, similar to HSV (probably easier to implement)
Perhaps: Start with alternative and assess reaction
Do not remove HSL or HSV as these are familiar to many
References:
Alvy's original paper on the subject
W3 CSS4 standard