Why, Plesk can also be a very successful choice if you ask me, cheap and feature-rich. Plesk UI is crisp and modern while I can't help thinking that cPanel was made by someone with an obsession for rectangles, corners and rather dull default skins. It's als easier for noobs to use Plesk.
I think that if a company offers a choice between Cpanel and Plesk like Serverpoint.com do , they have more chances to attract all sort of clients.