Tip: Upright-Torso Lunge

If your goal with lunge variations is to build quads, keep your torso upright and take short steps. Tibia should be vertical.

If you're looking to focus more on the quads, an upright torso position is best.

Taking a longer stride (with a vertical tibia) is more hip-oriented version; taking a shorter stride with a slightly angled tibia is a more knee (quad) oriented version.

So, if you're really trying to hammer the quads, you'd combine an upright torso with a slightly reduced stance length that creates a tibia angle similar to one involved in a standard squat.