I'll give it a shot...
For Symphony X, get "V: The New Mythology" or "The Odyssey".
Blind Guardian - I've only heard "Somewhere Far Beyond", but it rules.
Manilla Road - Go for either "Crystal Logic" or "Open The Gates".
Manowar (bought 'Kings of Metal' today) - first get their debut, "Battle Hymns" and then I recommend "Louder Than Hell" also.
For Iced Earth, I personally like "Days of Purgatory" or "Burnt Offerings" the most, because they have the best songwriting. The other albums are all good though too.
Helloween - get "Keeper Of The Seven Keys" parts 1 & 2.
Avantasia - they only have two albums... just get each one.
Stratovarius - either "Episode" or "Destiny".
Hammerfall - I like "Crimson Thunder" most, but "Glory To The Brave" is great too.
Fates Warning - "Awaken The Guardian" and "Spectre Within".
I've only heard "This Godless Endeavor", but it's an excellent Nevermore album. Highly highly recommended.
Running Wild - "Black Hand Inn"
Angra really depends on your taste, but "Angels Cry" and "Holy Land" are good. Only two albums I've heard by them.
Bal Sagoth - only heard "Starfire Burning Upon The Ice-Veiled Throne Of Ultima Thule", but it's fucking awesome. Get it.