808nm is the best wavelength for hair removal In term of efficiency and cost.

LASER HAIR REMOVAL is the process of removing unwanted hair by means of exposure to pulses of laser light that destroy the hair follicle.
The Diode laser system deliver a longer wavelength than the Ruby (694 nm wavelength) and the Alexandrite (755nm wavelength) lasers, but a shorter wavelength than the Nd: Yag (1064 nm wavelength) laser. This longer wavelength enables the light to penetrate deeper and is
theoretically safer than shorter wavelength lasers because it can better avoid the melanin pigment in the skin's epidermis. The Diode laser's longer wavelength of light thereby penetrates into the hair follicle without causing as much epidermal injury as the Ruby or the Alexandrite. This fact allows the Diode laser to be used on darker skin colors
than the Ruby or Alexandrite.