I really was sad when L's character died. Mainly because he never really ever got to live a normal life and he knew it. He was raised in that orphanage to be who he was then and nothing more. And for the summation of his life to be his death at the hands of the one person who could have been his friend under other circumstances, as well as that he knew the truth all along but because of supernatural reason's nobody could believe him, struck me as very sad.
Not so much for Light because I always thought he was a pompous a*****e of a character. His death was more like a sigh of relief in my case. In my mind I was thinking, "FINALLY!" Especially when he went out in such a pathetic way. I was smiling when he went.
Mikami, despite himself, I still felt sad for him. His whole faith, the "God" he'd worked so hard to serve, just came crumbling out from under him while the "God" became a hysterical mess and betrayed him.
Misa...bleh...I felt more for Jelus' and Rem's death than hers. She bothered me to no end.
Naomi I really felt bad for as well. She desperately wanted justice for her murdered fiance and for it to end just as she was about to reach it, with her having no idea how close she was, was very sad.
I also felt bad for Light's father. It's sad to know that even though he loved his son, and believed in him until the very end, he was being betrayed the whole time by his snake of a child.
Matt I never really saw the appeal in. He's more a fan-made character to me than anything else. People had so little to work with that they just took his basic attributes and turned him into whatever they imagined him to be. (In most cases, Mello's gameaholic lover) So his death was kinda bland to me.
I wish Mello's death had been a little more touched on considering his sacrifice, but I can understand why it wasn't for the sake of plot.