I really like the big Imai Zero X toy model kit and consider it the middle ground between the more accurate Aoshima die-cast model and the original Century 21 toy
The big Imai is very much a toy that wants to a model, but those big front wheels are a bit of a let down if you're looking for accuracy. It's a big kit and for some it might be worth trying to alter the thing to make it more screen accurate, but personally I prefer it the way it is as a kind of toy/model hybrid. I think most people are aware that the general rule is Japanese kits are great as long as you take on board that the makers like to include gimmicks like spring loaded firing missiles and battery operated movement. The Imai/Aoshima UFO Moonbase is a case in point - I think it looks fine as it was intended by the manufacturer, lots of fun features but not a lot like the one in the TV series. If I want something better, I guest gonna have to make it myself.
The Aoshima die-cast Zero X is much more for the model enthusiast who looks for accuracy, although I guess there'll always be nit -pickers who'll find something's not quite right. Personally I think it looks great, and that goes for the Captain Scarlet version too.
The highly sought after Century 21 Zero X toy. Not screen accurate at all, big wheels, friction driven lifting bodies and a battery operated remote control. All toy, but most collectors would give their right arm to have one!