Neither of which has any bearing on the expenditure of powers, as you could see if you actually read the text in question. Or perhaps already even know.
It is, for reference, perfectly acceptable to just say you like the game better if it works with it able to recharge itself and move on... it just doesn't work to say that's RAW without a written rule to back it up.
At any rate, a slightly more rigorous look at what I see as the rules surrounding this:
'Not expended' language can be found in
Reliable (p55)
Wizard of the Spiral Tower (p171)
Deadly Trickster (p174)
Staff of Power (p242)
All triggering while still resolving a power.
Regain the use of a power
Divine Vigor
Steel Blitz (p88)
Crescendo Sword (p88)
Astral Rejuvenation (p100)
Cold Steel Hurricane (p115)
Bolt of Genius (p154)
Sword Marshal's Action (p155)
Soul Burn (p170)
Spiral Tower Action (p171)
Shape Magic (p174)
Divine Miracle (p175)
Arcane Mastery (p206)
Epic Resurgence (p206)
Orb of Invasive Fortunes (p238)
Ring of Wizardry (p252)
Extended Rest (p263)
Can never occur during the action that expends a power, due to timing or action requirement.
Recover with a twist:
Epic Trick (p174) allows you to recover all daily powers, except this one. Unfortunately that validates neither viewpoint - they may be clarifying it doesn't work on that one just because it could completely break someone's game if there was a misunderstanding (unlike Crescendo Sword) or because if they didn't state it, it could work. This would have, however, satisfied my curiosity for at least any rules text to support the viewpoint
Expend comes up frequently in the ritual rules, with extremely clear language that you don't expend scrolls or components until the ritual is complete. If only the rules for other powers were more clear.
So, expend is always used for the language of a power while it's still being resolved instead of regain, heavily implying it is not expended / cannot be regained until afterwards, while regain is always used for when it's already resolved, implying you can't just say a power is not expended when it's already been used. Shaky, but the best I can see.
Other than those, the only text I can see on this is that you _can_ use a power if you can take the required action and that you require an appropriate action to take a power (p54 and p292). So we know you can't, for instance, use Crescendo Sword without a standard action available, and it can't be used until you spend that standard action - at which point the question still remains 'Does it count as used when I've declared its use or when I've resolved its use?' Technically there is a 3rd option of 'somewhere in the middle', which is probably most accurate for real life, but not helpful for in game
If you want to approach the common english side of things, you could look at the following conversations:
PC: Okay, I use Crescendo Sword on A
DM: Okay, he interrupts with a Disruptive Strike.
PC: Eh, okay, well my Crescendo Sword hits...
DM: Wait, didn't you already use Crescendo Sword a moment ago?
PC: I use Crescendo Sword on A, it does...
DM: You have to turn over your power card once you've used your power
PC: I will once I'm finished reading it!
to see that while the 'I use' does show up at the beginning, supporting the argument that it might be expended, there's also some serious silliness if you assumed use didn't also include resolving the power in question.