The corners will stay looking better with a coped joint.

Inside corners for baseboard are often coped because many times the corner isn't a perfect 90 degrees - making it more difficult to get a nice mitered joint. The other advantage of a coped joint over a mitered joint is that with seasonal humidity fluctuations (and over time) any joint can open up a bit, even a coped joint, but the coped joint will hide this from one angle.

Thank you so much brickeyee and dseng. Sorry it has taken me so long to reply. Your answers were very helpful to me and I appreciate your input!