According to last.fm, similar artists include:
Altaria
Axenstar
Dark Moor
Dragonland
Fairyland
Freedom Call
Lost Horizon
Nocturnal Rites
Power metal bands that make it into my top 50 played artists are (excluding PQ):
Blind Guardian - German power metal
Sonata Arctica - Finnish power metal
Helloween - German power metal
Manowar - American true metal with power elements
Avantasia - German power metal with many guest musicians, first 2 albums are heavy metal operas
HammerFall - Swedish power metal
Gamma Ray - German power metal
Iced Earth - American power/thrash metal
Stratovarius - Finnish power metal
Nocturnal Rites - Swedish heavy power metal
Ayreon - Dutch metal, rock operas & concept albums
Axxis - German power metal
Rhapsody - Italian power metal
DragonForce - UK (apparently
) power metal
Evergrey - Swedish progressive power metal
Edguy - German power metal
Freedom Call - German power metal
Kamelot - Norwegian/American power metal
Symphony X - American progressive metal with power elements
Hope this helps you!