They are a Power Metal and Symphonic Metal band.
Heavy Metal/Rock Metal
Neither. They are a psychobilly band (psychobilly is a sub-genre of punk music). Also, "metal" and "heavy metal" are the same thing.
Metal Church is a band that started in 1980 by 5 people that creates heavy metal music. This means that Metal Church is primarily heavy metal music band.
Power Metal - band - was created in 1987.
Death - metal band - ended in 2001.
Attila - metal band - was created in 2005.
Inquisition - metal band - was created in 1989.
Deadlock - metal band - was created in 1997.
Orpheus - metal band - was created in 2008.
Scrap Metal - band - was created in 1983.
Quartz - metal band - was created in 1974.