If you're in Tokyo, you should try the traditional "Kanto-style" oden, because it is really different from the Kansai-style. Whereas the Kansai-style places its emphasis on the clarity & flavor of the dashi (soup stock), the Kanto-style has a very dark soup stock and cooks oden in it for a looooong time so that the flavoring will permeate to the core. I personally prefer the Kansai-style myself (my mother comes from Osaka) but it's always fun to try the different styles of oden....

There is an oden restaurant called "Otakoh" in Nihonbashi and they've been in the business for 70? some years.
Otakoh Nihonbashi
2-2-3 Nihonbashi, Chuo-ku, Tokyo
03-3243-8282

They also have a branch in Ginza.
8-6-19 Ginza, Chuo-ku, Tokyo
03-3571-0751