Fair point. I’d still prefer the right arm*, but I think you could reasonably debate distal or proximal. Proximal has less chance of hitting the brachial artery and surrounding major nerves, but if you do hit them, you’re in bigger trouble than in the distal – where the median nerve and the brachial artery have split, making it easier to hit something but for that individual hit to be less severe.

* Another comment mentioned your glutes, which, yeah, fair if you could hit it from the side-on (and be fairly accurate, otherwise ouch, that tailbone).