I totally agree with Kimi ni todoke (but still ongoing), Ouran High school Host club and Death Note.
Tsubasa is nice, but I ended totally lost in this story and didnt understand the ending.
Why not Fruits Basket, nice plot, some very touching guest roles???
If you like plots like Death Note (mystery, manipulations...) , I would also recommand Monster (by Urasawa). Be carefull, it's very dark, but the story is incredible. Don't know how old you are, so maybe it's not convenient for you.