The basic approach to getting strong hasn't changed over the past several hundred years, despite Nautilus' and personal trainers' best attempts.

Lift heavy shit over your head. Put it down. Repeat.

To this end, barbell training is pretty much the gold standard in gaining strength. Machines are suboptimal in that they stress muscles in isolation from one-another, and remove the need for compound, coordinated muscle contractions that occur in literally every situation where you would want actual strength. Proper barbell training with compound lifts (squats, deadlifts, overhead press) trains whole groups of muscles at once, including the crucially-important stabilizers which are often neglected in machine-based training.

Starting Strength and Stronglifts are two extremely similar barbell training programs with a very large number of success stories. I've been doing the Stronglifts routine for three months, and am transitioning into Starting Strength as I make my way through the extremely thorough book (which goes into extremely helpful detail about performing the lifts with correct technique). In three months, my squat is now 195lb, deadlifts are 235lb, overhead press at 90lb, bench at 125lb, and barbell rows (which I'm phasing out in favor of power cleans) at 125lb. And I continue to add weight almost every single time I go out.

The numbers aren't super impressive by themselves, but for only three months from having starting at the weight of the empty bar (45lb), I'm seriously thrilled.