Rooted for Yagami as well, and Lelouch in Code Geass - guess I like antihero/ villain type protagonists. And they're both very similar type of characters.
That said, L was my favorite character in Death Note, followed by Misa, and then Yagami. Near and Mello couldn't even touch the Yamami vs L rivalry, and it all went downhill once L died. Yagami x L is up there with Goku x Vegeta, Guts x Griffith Naruto x Sasuke, Johan x Tenma, Kenshin x Hajime, and Shizuo x Izaya for lulz - as far as iconic status goes.
Also, speaking of Code Geass - Lelouch is a more detestable character than Yagami. The way he kills Euphie, and the whole Shirley deal was just horrible to watch. Although he did did kind of redeem himself by the end.
EDIT: Am I the only one who didn't like the Penbar's wife bit? For an investigator she sure played right into his hands, and he wasn't even very clever about it. The way Yagami acted was just so suspicious, and it just reeked of a deus ex machina insert to resolve the tension because he essentially dug a hole for himself.