I have had a go with both Enamels and Acrylics.
Regardless of what type of paint is used provided I prepare the surface properly I have had no problems with either.
Normally I will rub any plastic surface with some worn Scotchbrite. This will dull the surface to give the paint a 'key'.
Wash this with diluted detergent washing up liquid, to get rid of any residue from the Scotchbrite rubbing and anyd mould release oils
that may still be present. Allow this to dry and then give it a coat of matt white or grey primer.
Once this has dried, either paint should stay put without any problems.
However, if you intend to use matt enamel as the primer, and acrylic as the top coat,
be absolutely sure that the primer coat has dried thoroughly, or the acrylic could start to crack.
Hope this helps.