Resolution 300 PPI

 The higher the PPI the better the image looks because of its greater pixel density, Smaller pixels allow for a smother blend of color and shape which is another reason 300PPI looks better than 72 PPI. Exporting your design in 300PPI is better for a more professional quality look. 

PPI is pixels per inch 

which is the fixed number of pixels that a screen can display and the density of pixels within a digital image