OK, I've heard a lot of good things about True 20. I'll definitely have to check it out. However, do the True 20 core rules support things such as cybernetics, bio-engineering, innate powers, and curses? To give you an example of what I'm talking about, I'll explain a little about some of the NPCs of my campaign. Many of the NPCs that I have developed are unique in some way - maybe it's a mystical power, maybe access to advanced technology, but they have some unique trait that sets them apart from "mundane" characters. Of course, to be fair PCs should have access to this stuff to, although there might be a penalty attached.
#1 - The Wanderer. The Wanderer is known as one of the most fearsome gunfighters on the planet. He goes from town to town acting as a bounty hunter and mercenary. In spite of his renown, an aura of mystery surrounds him; not even his true name is known. In reality, The Wanderer is several hundred years old, cursed by the "gift" of immortality. Centuries ago he was a renowned soldier known for his arrogance and audacity. When it came for him to die on the battlefield, rather than submitting to death, he challenged the Grim Reaper to a dual and won! However, in doing so he was cursed - he had to watch everyone he was close to die off while he barely aged. Moreover, he can never stay in one place for more than a few days because disaster seems to follow him; anytime he stays longer than a few days in one geographic location some disaster strikes - crops dies, freak accidents occur, storms come out of nowhere. After living for several centuries, The Wanderer is now looking for a way to finally die. However, it is said that the only way for him to truly die and end his curse is to be beaten by a superior opponent in a fair dual... (In GURPS he had the Unaging, Unkillable, and Ridiculous Luck advantages, but had the Divine Curse disadvantage.)
#2 April - April is a soft spoken, kind, and somewhat naive creature. At a distance she looks almost human. However her pointed ears, and tiger-like eyes, and claws give her away. She is the result of bio-engineering by a mad-scientist (got to love them in pulp-adventures) seeking to create the ultimate bio-weapon. After escaping her creator she has tried to blend in with human society with only limited success. Her inhuman features make people afraid of her. Also people with the knowledge that she was created by combining the DNA of the fiercest mutants have run her out of town on more than one occasion. She now acts as an adventurer trying to find her place in a world that rejects her. (In GURPS she has the Natural Weapons [claws] and Dark Vision advantages, with a -15 point Social Stigma).
You can see from the two sample NPCs, that a lot of my inspiration has come from comic books, anime, and good old pulp. The powers characters should have access to should be unique, not a fixed list of spells. Also most unique powers have some type of drawback or curse attached to them.