I would have to vote: "None of the above".
Rather than giving us a new powerset that basically does the same thing as the existing powersets, just with new effects, I would suggest a more radical upgrade.
As toon's level, I would like to see the ability to choose from ANY power/powerset, even if it is outside of my basic class.
So, regardless of my AT, at level 6 (for example), I would like to be able to choose any of the following powers:
Touch of Fear; Build Up; Hand Clap; Assasin's (Attack); Smoke; Propel; Arctic Air; Confuse; Spore Burst; M30 Grenade; Dark Pit; Power Burst; Rain of Fire; Aim; Electron Haze; Shockwave; Murky Cloud; Conductive Shield; Power Shield; Healing Flames; Dull Pain; Earth's Embrace; Murky Cloud; Danger Sense; Reconstruction; Focused Senses; Darkest Night; Insulation Shield; Weaken; Triage Beacon; Glue Arrow; Power Push; Fire Breath; Ice Sword Circle; Telekinetic Thrust; Fling Thorns; Snow Storm; Darkest Night; Repel; Accedlerate Metabolism; Sonic Haven; Cauterize.
Or any power from any powerset available under level 6.
Some Mastermind powers may need to be left out as they are dependant on other MM powers. Kinda pointless to get "Upgrade Pet" if you don't have any pets!!
Of course, there would need to be some sort of limitation to this theory. I would suggest, that starting by level 10 or 12, if 25% or more of your toon's powers are from powersets outside of your selected AT, you loose your Inherit Powers. Though, if your AT is Dominator for example and all your selected powers come from other Dominator powersets, you would not loose your Inherited Powers.