The unrivalled best RPG making tool available.
Undoubtedly, one of the things that makes this program optimal for making RPGs is the amazing community support. Even after several years after its release, there are many active and helpful RPG Maker communities all over the web, most notably scripting communities.
With the new Ruby scripting feature, the types of games you could potentially make are almost limitless. Depending on the graphics and features of your game, you could make professional RPGs for commercial play.