Lots of genres, not repeating any Band (except Therion, but with 3 different styles). You cannot go wrong with this list, some nice Starts to any kind of Metal.
The list is sorted by year, but has not any particular order. Enjoy!

Created by:

Atrus | 10.06.2012

	1.	Queensrÿche - Operation: Mindcrime 1988
	2.	Atheist - Unquestionable Presence 1991
	3.	Therion - Symphony Masses - Ho Drakon Ho Megas 1993
	4.	Cynic - Focus 1993
	5.	Amorphis - Tales From The Thousand Lakes 1994
	6.	Dissection - Storm Of The Light's Bane 1995
	7.	Dark Tranquillity - The Gallery 1995
	8.	Opeth - Orchid 1995
	9.	In Flames - The Jester Race 1996
	10.	Therion - Theli 1996
	11.	In The Woods... - Omnio 1997
	12.	Sculptured - The Spear Of The Lily Is Aureoled 1998
	13.	Death - The Sound Of Perseverance 1998
	14.	Blind Guardian - Nightfall In Middle-Earth 1998
	15.	Tristania - Beyond The Veil 1999
	16.	Dream Theater - Metropolis Pt. 2: Scenes From A Memory 1999
	17.	Nightwish - Wishmaster 2000
	18.	Hollenthon - With Vilest Of Worms To Dwell 2001
	19.	After Forever - Decipher 2001
	20.	Emperor - Prometheus: The Discipline Of Fire And Demise 2001
	21.	Tool - Lateralus 2001
	22.	Borknagar - Empiricism 2001
	23.	Ark - Burn The Sun 2001
	24.	Arcturus - The Sham Mirrors 2002
	25.	Thy Majestie - Hastings 1066 2002
	26.	Threshold - Critical Mass 2002
	27.	Epica - The Phantom Agony 2003
	28.	Orphaned Land - Mabool 2004
	29.	Disillusion - Back To Times Of Splendor 2004
	30.	Demonoid - Riders Of The Apocalypse 2004
	31.	Wintersun - Wintersun 2004
	32.	Therion - Sirius B 2004
	33.	Mastodon - Leviathan 2004
	34.	Ayreon - The Human Equation 2004
	35.	Subterranean Masquerade - Suspended Animation Dreams 2005
	36.	Nevermore - This Godless Endeavor 2005
	37.	Gojira - From Mars To Sirius 2005
	38.	Neal Morse - ? 2005
	39.	Kamelot - The Black Halo 2005
	40.	Isis - In The Absence Of Truth 2006
	41.	Intronaut - Void 2006
	42.	The Faceless - Akeldama 2006
	43.	Amon Amarth - With Oden On Our Side 2006
	44.	The Black Dahlia Murder - Nocturnal 2007
	45.	Between The Buried And Me - Colors 2007
	46.	Behemoth - The Apostasy 2007
	47.	Myrath - Hope 2007
	48.	Xystus - Equilibrio 2008
	49.	Ihsahn - AngL 2008
	50.	At The Soundawn - Red Square: We Come In Waves 2008
	51.	Kylesa - Static Tensions 2009
	52.	Baroness - Blue Record 2009
	53.	Be'lakor - Stone's Reach 2009