I remember when I was looking to buy a Mazinger figure, I was a little confused by everything that was released, what was available, what was best, etc. Its still a little confusing. I eventually settled on one of the many Chogokin releases, the GX-01R. Its the original design and has all the main doo-dad gizmos(jetscrander with launcher, elbow drill missile launchers or rocket punch launchers, abdomen missile punch launcher, ironcutter fists). I didn't like that it didn't have a plider with bendable wings and instead had three pliders, one with hover wings out, another with hover wings folded for docking, and yet another jet plider just because. Heh, I just noticed that the jet plider can dock, but you have to remove the wings. It has a nice display stand to hold all the accessories too. Its a really nice set and the figure itself has some serious weight to it.
That said, my childhood's more familiar with Tranzor Z than Mazinger Z.
edit: How about a pic?