Both, because psi subclasses are a good way to introduce the psionic powers.
When a concept can have got its own subclasses or prestige classes has to be a class.
If the wilder becomes a sorcerer subclass I suggest the penalty for failing psychic enervation should be temporarily dazed condition.
The ardent, something like the psionic cousin of paladin, is an interesting concept, to be used in stories about conflicts and love-hate relations with clerics and other divine spellcasters.
The psionic rogue should be the lurker
I suggest the name "mentalist" for the psionic wizard subclass. In 3.5 the name was cerebromancer.
Now I miss some classes by Pathfinder, the Aegis (he creates an exoskeleton of ectoplasm, like wearing an astral construct as a powered armor), the medium and the spiritualist.