The thing about 'G's Revenge' it's never really meant as a companion to the other films, Toho cooked it up quick for their "Champion Festival" (That's what it was done for right ?). The film never tries to pretend to be a film like any that came before it, it's a simple tale about Ichiro's problems. Nothing more. The film doesn't even realistically try to pretend like the stock footage is new. (Which cannot be said for Megalon.) As a Godzilla film, the film reeks. And I must admit I don't like it too much myself. But on it's own merits, I think the film stands alone better then Megalon.
With that said, Megalon, from a quality standpoint, is a big pile of dog crap. However it's dog crap that I enjoy a lot.
I'd probably choose to watch it over G's Revenge most of the time. It follows your standard Godzilla plot to the tee, and you know what to expect. It's a better Godzilla film, simply for the fact that I think it's hard to call 'G's Revenge' a real G film, and the monster fights are new, and more fun.
