I'd also say that the style or formatting of your overall game appearance matters a lot in separating your game from the general, poor stereotyping of Maker games. You can completely replace all of the game assets with custom graphics, but if you continue using the default menu systems, the game remains easily recognizable as 'Another RPG Maker game'.
Good, custom graphics (whether high quality or of a simple, appealing style) are absolutely the first thing to get the potential players attention - first impression is the most important, and all that. But consider how you use them if you want to keep that good impression past the screenshots.