You should really check out Fairyland, specially the "Score to a New Beginning" album, though I like them all.
I know plenty of straightforward Power Metal bands that I could list here, but this one match two genres as it's symphonic.

Sample here:

Some bands I dig:

Power: Machinae Supremacy, Iron Mask, Edguy, Lost Horizon, Sacred Blood, Cardiant, Dreamtale

Prog and Avant-Garde: Devin Townsend, UneXpect, Ascension Theory, Green Carnation, Arcturus, Solefald, Vulture Industries, Ved Buens Ende, Vintersorg, In the Woods..., Peccatum, Ulver (mid era), Infinite Singularity

Sympho: Acacia, Neverstar, Mysterya, Reign of Sirius, The Storyteller