Amazon Cloud Image istance most suited for R data mining
It very much depends on the calculations you are doing as well as the tools you are using to implement them and the size of data you are working with.

Some small rules of thumb:


R processes (generally) tend towards being RAM bound, so you want may want to get a RAM optimised
R Studio IDE has a profiling tool you can use to check how your code executes and where the time is spent
It may be easier and cheaper to optimise code before scaling with tools like data.table and RCPP


ML models are likely not going to be effected by this, more your data prep, check the profiler

If you are REALLY keen on getting the model running fast, look into the GPU/TPU instances, however, in the case of R using caret, I don't know if it will utilise these assets. Do your research first as these are the most expensive flavour of EC2. TPU units are (from my limited research) specifically optimised to tensorflow ML.


A plan B/alternative would be to work in aws Sagemaker notebooks to start. Then you can abstract away all the faff of managing the EC2 and just focus on building the ML.

For extra credit on your EC2, use one of the R community AMI's put together by this lovely person: http://www.louisaslett.com/RStudio_AMI/