I have a theory about game-editors and gamedevelopment.
Many editors was developed internally in the game-companies as internal development tools and they were usually developed for a specific game or a specific type of games. The best example are the numerous first-person-shooter editors: Crytek's CryEd, Valve's Hammer, Epic UnrealEd. Each of them was developed for a specific type of games - first person shooters (FPS) - and affords for the development of these types of games right down to the options you have with the camera and the way you make levels in them.
They are very effective tools, but the effectiveness comes with a trade-off: they support the development of FPS-games, but are difficult to use for anything else. If you want to use them for a non-FPS-game, you'll either won't have the performance boost from the editor or might even be forced to work against the editor.
I have two examples of this:
A while back we wanted to start a modding group and make a FPS-game with localized, directional gravity, - where specific, small areas in the game had their own gravitational direction. Our programmer examined UnrealEd and discovered that the gravity was set globally for a whole level and was very hard to alter (you had to do modification to the engine code). So we didn't go any futher with it (you can read about the idea here: Eschermod. Feel free to throw a couple of millions at me if you want to fund the development of it, Epic)
Another example (just rumoured) is about a group that wanted to use Valve's Hammer-editor to make a Real Time Strategy game. They turned to camera vertically downward and removed all controls tilting it, so it was fixed downwards; - top down look-style. However, they were unable to remove the sound of footsteeps when the camera moved around. I could probably have come with a hack that could have fixed it, but that just proves my point: I'm working against the purpose of the editor, because the editor doesn't support my type of project.
I suspect that the more specific the editor is toward a given game(-type), the less effective it will be with other types of games; an inverse correlation between effectiveness & versatility. Creators of general purpose game-editor (like Unity3d, Torque, Ogre) has to balance versatility and effectiveness when they make their editors.
The logical consequence is that you shouldn't pick an editor because it is the most widespread or most powerfull editor around, if it doesn't fit your purpose. In fact: all that power might even work against you. You should pick the editor that fits your purpose the best.
(Another logical consequence: if you want to make a game that's completely radical (which happens extremely rarely), an editor might not be a good idea).