The simple drag-an-drop feature makes it so easy that you don't need to be a designer to design stunning graphics. Choosing the "best" graphic design software is always tricky, as it's really a matter of opinion and depends on what exactly you want to create. Every designer needs to decide for themselves what software works best for their design style, needs, medium and, of course, client.
Canva: Canva is an amazing free web based app. In fact, one of the best free graphic design software for beginners as well as professionals.