Can be from any genre. Mine is when an acoustic guitar comes in towards the end of a song and totally changes or reframes the mood/energy (see "Money" by Widowspeak)
Wheel of Time by Blind Guardian is one of my all-time favorites. Looking at the other bands you linked, I'm guessing you've already heard it; but for others reading this, clicky the linky!
Symphonic Metal is such a small genre though... I want more! Q_Q