Personally I'm a big fan of solid carbide end mills. Cobalt is good too. and is TiAIN-TiCN. But I feel carbide is the best for both wood and plastics.
Resin will require a slower spindle speed so you don't melt it into a ball of goo. 10-15K rpm at a 70imp feed rate with an upspiral bit will probably work well for the resins. Keep the depth of cut to about .100 - .200 inches.
See the attachment too.. strictly according to the atachment resins should be run at a spindle speed of about 3K rpm. But you router would have little is any torque at that speed. In rapid feed rate and upspiral bit will help compensate for this.