I think the choice depends on you programming preferences and experiences. I usually prefer programming R. If you decide on using R, a good starting point for text mining in R including Sentiment analysis can be found here: http://tidytextmining.com/
For sentiment analysis, I am using Python and will recommend it strongly as compared to R. As Mhamed has already mentioned that you need a lot of text processing instead of data processing. Also, you can find all libraries and many small supporting tools implemented in Python. There are many small suites available along with Python code which can help you to implement your logic and compare with others. Most of the researchers working in sentiment analysis are working in Python.
Maye you can provide some good literature to start with python in text mining and sentiment analysis. Also a more detailed overview of python packages would be helpful.
First of all thank you all for your contribution to my question. Could you please tell me if there is any difference between the social media types regarding the program you use to conduct a sentiment analysis? Or you can use both Python and R in any kind of social media you want?