Power metal, you say? I'm not very well-versed in it, but here's a few bands I do know (descriptions will be shorter than usual, due to my relative lack of knowledge with regard to this genre):
Iced Earth -
Power/Thrash Metal
Probably my second favorite power metal band, Iced Earth are amazing almost solely because of their old vocalist, Matt Barlow. That man's voice just oozes emotion when it needs to and pummels your face in when it needs to. Their reliance on Barlow's vocals really shows when you listen to the albums before and after he was in the band, which really suffer at the lack of his vocal talent.
Blind Guardian -
Power Metal
Power metal with an awesome vocalist and nerdy concept albums (theirs being about the Silmarillion). This seems familiar.
Dragonforce -
Power Metal
Dragonforce are a terrible band. They weren't always, though. Their first album is one of the best power metal albums I've ever heard. Unfortunately, they ended up gobbling their own cocks and ripped themselves off more and more with each album. They suck shit now.
Symphony X -
Progressive Power Metal
Symphony X are extremely talented musicians. They are easily my favorite power metal band, mostly because they do power metal differently. There is a lot of prog in their music, as well. They have a few huge epics that surpass 20 minutes across numerous movements, a kind of song typically reserved for prog. They also shift time signatures and tempos regularly, most evident in Inferno, linked above.