Kiva's story concept was better because of Otoya's side story. Den-O was full of godmodding pre-repeat mayhem to me.
*Cough* Ahem. Kamen Rider W concept of the idea is not bad, probably unique as crossover with Goseiger. I liked the writer had the idea of Metalder design way although unique. Battles are fine, different from Agito or Blade. Akiko is too annoying for my taste, not better than like kind-hearted Mana-chan because is more acting like selfish spoiled brat one of those anime she imitate. Kirihiko is my fave, but after his death I did truely hated Saeko. Ryubi Sonozaki was sounded as Seto Kaiba. Accel's development story is great for the at least; just missed the motorcycle stunts ever since I did watched Godai from Kuuga.
Hey Den-O was the first to have another mind inhabit a body concept. Kiva sorta tried to do something similar. W is just a better Den-O.
Den-O is not as bad as people make it out to be.