I don't have as much expertise on the science as a lot of folks, but if you have sarcoplasmic hypertrophy, sarcomere hypertrophy, and CNS efficiency, it's the latter two that will help get you strong. High reps and endless pumping sets focuses on the first, HST more on the second I think. The really heavy work with low reps tends to develop the CNS more, and routines specific to a sport will be more optimal for this, as Scientific Muscle says.
However, for most of us who are far from our ultimate potential for sarcomere hypretrophy (more/thicker muscle fibers) I think we'll gain more strength long-term by developing that as much as possible. After all, CNS efficiency just helps you to better use the muscle that you have. I'm thinking develop hypertrophy as much as possible, then when it's very hard to add more, more specialization on training that is more CNS-specific (like heavy singles/doubles) will help maximize the ability to use what you've developed.
Having said all that, the principles behind 5x5 seem very close to HST, and Max-Stim is based mostly on the same science as HST. So you have HST with rep ranges 15 down to 5, 5x5 with rep ranges mostly 5 down to 3, and Max-Stim's reference program uses 20 total, though this can vary. However, Max-Stim because of the M-time allows use of heavier weights than ordinary set/rep schemes, probably as heavy or heavier than the 3x3 ranges in the 5x5 schemes, but still with enough total reps to be fully hypertrophy inducing.
So on the continuum above, all three should be good for hypertrophy, with HST leaning a little more toward hypertrophy than CNS development as compared to 5x5. Max-Stim may give us the best of both worlds, though perhaps not as much sarcoplasmic (non-strength producing) hypertrophy, as there isn't much pump when you're trying to eliminate the fatigue produced by multiple reps. Like Scientific Muscle I'm also trying it.
Time will tell...