It depends on the game. Each engine has different characteristics. RPGM is better suited for RPGs, RenPy for VNs, and Unity for ultra-high-end 3D graphics.
ok yes....... i will admit...... i am going to say renpy also....... but i have a big soft spot for rpg-m.... the 'vibe' you get from such games is unmatched... for me anyway, i could not tell you why, but i get a very enjoyable feeling when a game is using rpg-m.... it is a large sad problem for me there are not many games in rpg-m that are so lengthy story-wise compared to many on renpy...... i always like to see a traditional visual novel format using rpg-m!
RenPy will always rein supreme, but if a game actually offers good fun gameplay then RPGMaker is also really valid, take something like Black Souls for example.