I have used all 3, and happen to mainly use Installatron. However, Softaculous seems to be offering the most and potential customers have realised this and so I believe are starting to look for hosting with softaculous (rather than Installatron or Fantastico) more and more often now.

As it provides the most scripts and fastest/easiest installations, I'd probably say Softaculous is the winner out of those 3 these days.