Can't speak for Spyder, but one killer feature of RStudio is the ability to easily make C++ modules that your R project uses (RCpp rocks - you can ignore most of the annoying things about C++). They compile and link with zero effort. Also the ability to easily install modules. And browse documentation. And create projects in R or RMarkdown. Create modules, basic scripts, web apps. And publish things. And see your data in a spreadsheet format. And inspect all your objects/data/functions. All in one place.
Aside from RStudio, I love R's lispy/apl-ish semantics, and easy integration with Fortran/C++ (and a host of other languages, including Java, Haskell, Ruby, Prolog, Lisp, etc...).
I'm sure Python is great, but R is made for stats, is amazing, and RStudio beats every IDE I've ever used, regardless of language.
Aside from RStudio, I love R's lispy/apl-ish semantics, and easy integration with Fortran/C++ (and a host of other languages, including Java, Haskell, Ruby, Prolog, Lisp, etc...).
I'm sure Python is great, but R is made for stats, is amazing, and RStudio beats every IDE I've ever used, regardless of language.