Help building a graphic design PC for a business

Hey guys! I am trying to figure out what I need to put into a PC for graphic design (heavy photoshop and Corel draw use, a few other design softwares occasionally) this will be used heavily, daily. The issue is we only have $500-700 to spend. We don't need a monitor, just the tower. And I can't decide if an Intel i5 or i7 would be better. Any help is appreciated, thank you!