I'm not certain how effective this Increased Stamina is. There's hardly any info floating around to concretely say that it's useful, so I would go with Level Head 4. That Frenzy immunity is invaluable.

At the moment something is very wrong with the R300 races. While Frenzy drastically affected NPCs pre-R300 (Frenzy them and watch their stamina drain like water through a sieve), in here they are nigh-useless.

For some reason R300 Frenzy hits you like an absolute truck ~30% stamina loss easily = Game Over. NPCs get very minimal (if at all) stamina loss. I trusted SE to be careful and fair but now I'm incredibly disappointed that they overlooked such a big and obvious problem in their testing.