It depends on your lab/institution, and sub field, but I think Python is more common in bioinformatics than R nowadays. I prefer R - and personally developed many of the most widely used Bioinformatics packages in R, but have mostly shifted my lab to Python because of more extensive library options. Most of the big institutions - like large sequencing facilities are using Python. If you’re hiring teams of software engineers to make professional quality tools, it’s a lot easier to recruit for Python.