Are there any maiden songs that could be called power metal?
What do you think constitutes power metal?
Is it the fantasy aspect? If so, then they've had plenty of power metal songs.
Is it the heavy, symphonic aspect that is typically attributed to power metal? Then no, I'd say they have not.
Or is it maybe the more 'speed metal-esque' aspect? Someone more versed in speed metal could probably point out some Maiden songs that qualify, but I think early, Dianno era Maiden probably had the most speed metal qualities to it.
While they may have flirted with a power metal sound at times and maybe even influenced its development, I don't think Maiden has ever had a 'true' power metal song in their catalog. They've never played anything as... over-the-top and bombastic as most power metal, but I can be a genre-snob sometimes, so take my opinion with a grain of salt.
I also think it would be awesome if Maiden had an album that was musically like Painkiller.
For better or worse, Maiden have never been as adventurous as Priest. They have their sound and while they have tweaked or even stepped outside of that sound a bit, they've largely stuck to it since Bruce joined. I don't mean this to sound like they're stagnant or unchanging, but put a Bruce reunion-era song up against something from Number of the Beast or Piece of Mind and both sound like Maiden.
Priest, on the other hand, dallied with all different types of sounds throughout their careers: speed, symphonic, thrash, glam, nu-metal, blues and straight up metal. I don't find their catalog to be consistent at all and one could maybe fault them for just following trends, but the fact is they stepped out of their comfort zones multiple times and did something different.