Findings:
I honestly don't get the hype around R's plotting capabilities. ggplot2 is nice, but far too magical to be easily understood by beginners.
Python offers more intuitive memory management than R (which is really more a statement on how bad R is at memory efficiency).
R blows Python out of the water when it comes to expressing concise and readable linear algebra/stats computation. Done right, base R looks like mathematical pseudo-code.
R's non-standard evaluation is an under-appreciated killer feature. I've seen complex and powerful DSLs implemented implemented in base R. Python has some support for this kind of thing, but nowhere near the level of R.
I tried the Tidyverse and found it to be too magical and unstable. In general, the R package ecosystem is weird. Look at Stack Overflow and you'll find people touting all sorts of different packages to do simple operations. Needing to download a million random packages from grad students of the internet is a recipe for disaster.