I work with a few data scientists and many are porting over to python, its just more flexible and more open source libraries out there sklearn / pandas / tensorflow.
I was a big Excel/VBA user having worked in Finance for years and I thought it was the perfect tool because you can do almost anything, just very slowly.
I would say it's the best tool for data analysis, literally anything you want to do can be done within a few lines of code because its all wrapped up in functions.
I've built my entire end to end process from scraping, Betfair API, train/test models to sending out info in emails, files or posting to DB all in R.
If you have a reasonably powerful machine with at least 16GB of RAM you can crunch millions of rows very quickly.
The best thing for me is if I want to try a new model, you can format the data, then put it through 4 or 5 different models with cross validation and easily compare the results, so if I have a new idea (which happens daily) I can test it out very quickly.