Why should I choose, when I can make the players do it?
Flexible Caster:
Choose One:
Self-Sacrifice: Whenever you use a metapsionic power, you may choose to instead take damage depending on the number of extra slots you would have used. Each Minor Slot is worth 2d10 HP, whereas each Major Slot is worth 4d10 (Numbers not finalized)
Multi-Faceted: Choose one feature you've already taken. Whenever you take a long rest, you may choose to switch between the choices within that feature. (For instance, if you originally chose Twinned Spell from Rapid Caster, during a long rest you may gain the ability to use Quickened Spell and lose the ability to use Twinned Spell, and vice-versa.)
Rapid Caster: Choose One: Twinned Spell: Whenever you use a psionic power, you may choose to, in addition to the original slot, use an additional slot one level higher than the original (In the case of Major slot powers, you simply expend a second major slot) to use a free action to cast the power again. This can only be used once per turn.
Quickened Spell: Whenever casting a Minor or At-Will power, You may choose to use an additional minor slot to cast that power as a minor action. If that power is already a minor action, then it becomes a free action.
Consistent Caster:
Choose One:
Bouncing Spell: Whenever you cast a psionic power and fail to break resistance, you may expend a minor slot to re-cast the power against another enemy as a free action. You may only do this once per power.
Focused Spell: Whenever you cast a psionic power, you may choose to expend an additional slot equal to the level of the original slot (For at-will powers, you expend a minor slot) to gain advantage on the attack roll. If the attack targets multiple enemies, you only have advantage against one enemy
Intense Caster: Choose One: Maximize Spell: Whenever you use a psionic power that has any variables (I.e. Dice, Modifiers, etc.) you may spend a Major slot to automatically maximize all of these variables. All dice are automatically equal to their maximum value, and anything relating to an ability score is automatically set at 10.
Lingering Spell: For an additional minor slot, you may extend any power that lasts less than one round so that it lasts until the end of your next turn, or add an extra round to the length of a power that lasts a round or longer.
Distracting Caster: Choose One: Jarring Spell: You may spend an additional minor slot to make your spell disrupt a Psion's concentration. The concentration save DC is 15+Proficiency
Dazing Spell: Whenever you use a psionic power, you may choose to use a minor slot to make an additional Psionic attack roll against your opponents Fortitude or Will resistance (whichever is higher.) If you succeed, you may choose to halve their movement or make them lose the use of their minor action until their next turn.