Quads have been my Go-To for years.
You do however want to be careful about Hitting or Injecting next to a Nerve (you'll know if you hit one).
You can Irritate the Nerve, and this will cause PIP (post injection pain).
As far as Nicking a Vein ~ No Big Deal.
But you don't want to do an Intravenous Shot either ~ so if you Aspirate and Pull up a Lot of Blood.
Just move your Injection Site an Inch or so over.......................................... JP
P.S.
If you look carefully, you can usually see the Surface Veins.