One reason (at least for me) to not want to use either Porcupine or Snowboy is to avoid non-free software. Of the available free software options, which one would be best?
@voice, when you say non-free, I am not sure what you are referring to, because Porcupine and Snowboy are both free to use. With Porcupine, there are several wake word that you can use. If you want to create your own wake word then you have to signup on there web sign and create one, but you will have to do it every 30 days, because it expires, this is still free. Now with Snowboy, it is also free to use but you have to create an account on their website. So, if you are just talking free, then the two options above will work for free. As I think about it you maybe talking about open source when you refer to non-free, not sure, but I hope this clears a couple of things up.
Sorry, but it seems that you and I are attributing different meanings for free software.
What I mean is free as in speech, as related to freedom (not only price). It is also often called open source (or FLOSS: Free/Libre and open source software).
It seems to me that both Porcupine and Snowboy are proprietary software (aka non-free by the “freedom” definition).