Definitely Renji.
Who wouldn't? Because of him I urged myslef to continue watching Bleach. Plus, he is HOT. And who wouldn't
resist his tattoos and especially when his hair is down. :3
Also his loyalty to (unfortunately) Rukia and his passion. My friends think he's scary (wonder why).
Through there are also some who caught my eye, like Shuuhei and Grimmjow but I still stick with Renji. *fangirl squeal* XD