Good games can be made with either engine. But recently we've seen alot more casual hobbyists deciding they are professional game makers and posting what they have on steam greenlight, for example.
I think that at the moment Unity might a bit more of a problem because to make a good RM game you need a decent story, because that's what the engine lends itself to (it's not graphically impressive, it takes a lot of effort something really engaging within the gameplay alone, it's more about writing(imagine To the Moon with a rushed story, suddenly A to D as a game imo)and observing things. But writing that takes time, and the hobbyists trying to push something onto the market in a month or less cannot be bothered. There are plenty of pretty terrible games on RM but I think that quite a lot of them had more thought put into them than the terrible Unity games we see. (example, there was a sample clicker game on unity, it was a copy of cookie click pretty much, and someone tried to sell it on steam, the only difference make was the graphic of the cookie. I have no doubt that it was a scam, but oh dear I hope noone has even done that with a RPG Maker game sample. I don't want to take sides hugly here but the terrible RPG Maker games I've seen have had more effort put into them than the really terrible unity games. Maybe I'm just looking in the wrong places.