Now I have seen DeathNote but not Code Geass. I will say that they are decent but nothing great. DeathNote in my opinion was just two people stating how smart they are than their opponent. And then the second half of the series went downhill for me. You probably can guess why and if you dont know I dont want to say cause it might spoil it for people. So I will have to say that there are a great deal of other anime series that are far better than DeathNote and Code Geass. My suggestion is to look and watch past anime. I would have to say that Cowboy Bebop is a far better anime for its plot and use of music. Cowboy Bebop also had a more beautiful and poetic ending. Death Note you already knew what was going to happen to the main character so I knew what to expect.
I also have to agree with LenMiyata. Ghost in the Shell was in my books a masterpiece. A work of art. They created great characters and even a great mystery behind it all. It also let you dive into a different perspective of a futuristic earth and used works like the Catcher in the Rye (I believe so) as a somewhat basis to some of the characters.