Great question. It comes down to preference. cPanel and Plesk are owned by the same company (Oakley Capital) so in the future I wouldn't even be surprised of these to being molded into a single panel. I like when people want to compare control panels and I always say it's like comparing cars. First, it's your budget, what can you afford? Secondly, it's your preference. What are you requirements? If both panels meet your requirements then it comes down to other preferences, such as style. Maybe you think Plesk looks better than cPanel or vise versa.
Lets look at things in a big picture. Plesk, cPanel and other control panel software are very popular choices and thousands of people around the world use both. So they are working options. For me, if I was to compare the two. I like cPanel better because it just works for me. Someone else, might like Plesk better because it just works for them. Both of the choices are great, and they will do exactly what you need and some.
