I am using polycarbonate (lexan) for detecting alpha particle due to radon and fast neutron as well. It's flexible and satisfactory using electrochemical etching.
It depends on your application and abilities of your lab. Polymeric detectors are very different and have some advantages and disadvantages. For example lexan polycarbonat is very convenient to use and the appeared ECE-tracks are very strong in compared with CE-track, but the sensetive range of alpha energies is smaller than PADC detectors or LR-115.