Anyways I am asking also do folks prefer be unique demons, or unique devils? As unique demons you fight to carve your own domain in the infinate layers of Abyss among figthing other demons for power. While in Hell there is chance to become Archduke and one layer lords.
Anyways stats are simple; you gain bonus point to your stats based on your class levels only
. Meaning 4-6 class levels give 1, while 8 levels give 2 points to spend on your stats.
Now the actual base stats are determined by how they are shown in MM, MM III and so on whatever is your base race source. Note that your base race can be already generic established demon/devil (so yes, you could pick balor or pit fiend as base race and add templates and class levels on it and be done with it but that's boring
). Or it can be magical beast or other creature subtype (unicorn demon? Nymph devil? YES!).
So if you want high stats focus carefully what templates you take. As most +1 templates give +1 CR or +3 CR with higher HD. Also as alternative instead template you can use CR to purchase outsider levels. Each 1 CR gives you 4 HD as outsider. As note if your outsider HD + class levels go beyond 20, you can select epic feats from Epic Handbook at that point. Also bit repeat; remember at end of creating base creature you get Baatezu or Tana'ri subtype (and it's perks) for free.