Which is good for exploratory data analysis
It is a really hard question to answer because you might have to choose the language according to your need because both the language has equal importance in field of data science.
My preference for exploratory data analysis is R because it is a language build for statistical analysis and is more preferable over Python for statistical operations.
You can use Python though in case if your code is to be used by many users or made in a group of good amount of members. In that case you should use Python it might be more complicated than R but the virtualenv (virtual environment) feature makes this language highly efficient and the code can be executed in any OS. Only in this case Python is preferred otherwise R is a good choice.