Are we discussing character wise, or cosplay wise?
Because L is fun to cosplay, while Light is just awkward because you're trying to be all dramatic, yet people come up to you and are all "can I sign your Death Note?"
Character wise, I think L's quirks make him a wonderful character, and he is a lot of comic relief on an otherwise overly dramatic anime. On the other hand, L is a lot stupider than he made himself out to be. Light was intellegent, smart, and godly at the same time. L is just kinda cute. Matters what you like better in a character.
Cosplays: Brock (Pokemon) 95%, L (Death Note) 100%, Kurapica (Hunter X Hunter) 100%, Bikky (FAKE) 40%, Count D (Pet Shop Of Horrors) 70% Dave Strider (Homestuck) 95%
New York Comic Con 2012:
Friday: Sober! Gamzee Makara (Homestuck) 80%
Saturday: Mituna Captor (Homestuck) 80%
Sunday: Mituna Captor (Homestuck) 80%