Water with detergent dissolved in it should have small angles of contact.

Explanation

The clothes have narrow pores or spaces which act as capillaries . The height of liquid in capillary,
`h=(2Tcostheta)/(rrhog)`
`therefore` Height h is proportinal to `costheta` (Where `theta` is angle of contact). As the `theta` is smaller for detergent , therefore `costheta` will be large . Due to this the detergent will penetrate more in the narrow pores of the clothes.