I like both, but I usually fall on the side of Classicvania. Part of this is because I feel the Metroidvanias failed to evolve much. Where most of the Classicvanias tried something fresh with each new outing- Simon's Quest experimented with RPG elements and open exploration, Dracula's Curse had 3 characters and branching paths, etc, Symphony was kind of the zenith of the Metroidvania style, and the later ones tended to be (while still good) rather pale imitations aiming to ape its success.
As for 3D 'Vanias...I like the N64 games, even though they have their flaws. I enjoyed playing LoI. Never played CoD, and didn't really enjoy LoS.