What is the better to pre-process data, MS-Excel or Python/R
I mean most of the time it's very much about preference really.

If you want any indication on when to use what:


MS-Excel can only handle so much data. Good for quick analysis of small data but neither good for production or middle to large amounts of data
R great tool for calculating stuff, running models, etc. Pre-Processing is good, lots of libraries to use. Some people don't like using R for production pipelines but I know companies where this is working just fine
Python is a great overall language for pre-processing and creating production worthy data pipelines. So if you want to have a scalable, reusable pre prcessing pipeline this is certainly one of the ways to go


Of course Excel has the lowest learning curve compared to R and Python. The latter ones are similar in that.