Psytrance has all the subgenres in it that we all know and love/hate, but I personally seperate Goa from rest of Psytrance for various reasons. Somehow I've always just made a clear distinction with goa and other form of psytrance. It's definitely subjective but it, for some reason, just makes perfect sense to me. There's just something about the sound that makes the clear difference between the two.
Actually I also seperate psytrance from full-on, darkpsy etc. because there are releases that don't really fit those (subjectiveish) extremes, like Fragletrollet, Cybernetika or Principles Of Flight. So those are just psytrance and others that fit the bill on something like full-on are a subgenre of psytrance.
So kinda like this..
Psytrance
-Goa
-Psytrance
*Full-on
*Darkpsy
*Psyprog
*Suomi