For me, it's less about the machines and more about the body weight exercises. Here is one of my interval workouts:
5 rounds, no breaks -
25 pushups
25 Burpees
50 Mountain Goats
200 meter run
25 squat jumps
No weights or equipment needed. Doing these types of exercises has helped my stamina, strength, power, and quickness. We do crossfit on a regular basis which is all about transitioning from one exercise to another quickly and pushing yourself hard. If you are interested, make sure you go to a reputable gym where they will also train the movements (how to do a proper squat, proper lunge, etc.), otherwise, you may get hurt.