Action anime:
Claymore (ignore epi 25,26)
Naruto (ignore fillers)
Code-Geass S1 S2
Fullmetal Alchemist Brotherhood (still ongoing)
D-Grayman
Gunslinger Girls
Law of Ueki

Comedy anime:
K-On
Lucky Star (1-4epi sux coz director nuub,later chg, den rest is nice)
Seto no Hanayome
Sumomomomomo

Slice of life:
Honey & Clover

Supernatural:
Hell Girl S1 S2

Romance/Comedy/Slice of life:
Chobits !!!
Toradora
Midori no Hibi
Clannad