Rstudio is nice, no doubts there; however, I find myself avoiding language-centric IDEs. If one uses R most of the time, it's fine, but as someone who usually writes in multiple languages in a day, I find myself appreciating emacs' modes more (of which the Julia one is fine). It's also why I like the fact that the semi-official Julia IDE, Juno, isn't a standalone application (it runs in Atom and is nice, if one doesn't mind the performance of Atom...)
edit: spelling