What are properties of an ideal electrical insulating material?

The following are properties of an ideal (electrical) insulating material:
(i)  Low  dielectric  court(high  dielectric  constant  if  used  in  capacitors  for  storing energy.)
(ii)  Low power factor.
(iii) High dielectric strength.
(iv) High insulation resistance.
(v)  Adequate mechanical strength to face service condition.
(vi) Resistance to heat and temperature.
(vii) Low moisture absorption or water proof.
(viii) Good chemical stability and chemical proof.
(ix) Fire proof.
(x) High volume and surface resistivity.
(xi) Good surface finish and machining.