Izaya was probably my favorite character while watching Durarara. I probably liked him most because I tend to like the silly mischievous characters.
Two of my favorite moments were when he stomped on a girls cellphone while laughing like a mad man, and later when he jumped on the same girls boyfriend. She deserved it by the way.
I love how he can do the strangest things. and still be cool despite it.
And despite the fact that he can be very strange and silly, he's still a bad ass when it comes to fighting.... Unless Shizuo is involved.