If I follow the web site posted above
Hunter (S-Tier)
Beast is top, Marks good, Surv worse
Mage (S-Tier)
Frost top, Fire good, Arcane terrible
Warlock (A-Tier)
Affli Demo both top, destr worse
Personnaly prefer affli for more dots and face tanking
Paladin (A-Tier)
Ret top for faster lvling, whatever spec you do start with 70% no interrupt healing I say… personnaly prefer holy so you can heal or tank dungeons as it suits you, just slower to kill mobs…
Rogue (A-Tier)
2 tops
Combat faster lvling more hit more damage
Sub safest to survive
Personnaly i start combat then respec sub at 30
Druid (B-Tier)
Feral top. Period
Once you reach 20, Id consider them S tier. You cant fail with druid and super fun. You can port to kalimdor anytime, you go 30% run at 21, 40% at 30, fastswim and water breathing at 16, free from roots and slow, 2 great buffs, can tank elites, never need to drink, can heal every fight. You can go stealth and you never need to lvl your weapon skill.
Priest (B-Tier)
Disc top, slow but immortal, shadow good at 40 for more fun and damage
Shaman (B-Tier)
Enh top, faster wolf casting for escape, faster lvling, les mana use
Warrior (C-Tier)
Arms top, fury good, prot terrible.
Must always fight green mobs or same lvl.
Can tank any dungeon in any spec