Rubber.
Exception would be nylon with greasible 'pins' for situation where want to minimize every bit of suspension compliance.
Penalty is more maint and slightly higher NVH.
Reaction strut bushings are place I would consider poly
But then strut rod placement must be checked and if needed, bushing thickness modified.
Otherwise you may find the LCA being pushed back (or forward) from its proper position - especially when using nylon or poly LCA bushings.