While I don’t have any experience with either of these cars I think these are two very important questions while thinking about this.
What is his overall driving experience?
Specifically on track?
Both of these cars are probably going to be pretty fast on track, even out of the box. If it must be one of these two, I would think one might be more forgiving at the limit than the other; simply by the nature of the stock handling characteristics. Just spit-balling a guess that’s probably going to be the R, but that’s just an educated guess. Bigger picture if he has little to no track experience, I would think something with less power, lower absolute handling limits and maybe more neutrally balanced might be more appropriate while he learns. This also depends on how serious he/you thinks he will be about tracking it. Maybe this isn’t such a big deal if we are just talking about one or two learning events a year.
Just food for thought, take it as you wish.