The BEST exercise

Yoga. Pilates. Mixed martial art. Qigong. Turbulence training. Cardio. Racket sports. Boxing.

The list is endless... every year or so, "new" discoveries pop up and are touted as the BEST form of exercise. Is there such a thing as BEST???

I don't think so... Let's look at what your goal is...

Strength? Flexibility? Stability / balance? Endurance? Fat loss? Bulk? Toning? Stress release?
etc

At the risk of simplifying, exercise routines can probably be boiled down to

Strength ---------------------- Stability and balance
eg, weights                               yoga, pilates, taichi

Somewhere in between is people who do "functional" or "core" movements with weights - eg, woodchopper, etc

Can ONE exercise meet ALL the goals?
It is quite unlikely... although it must be said that yoga although typically classified as stability and balance exercise, can also build strength. In fact, some advanced yoga movements are challenging even for those who can lift heavy weights.

Since it is difficult for ONE exercise to meet ALL the goals, it is perhaps wise to choose several physical activities.
For example, those who lift weights should not neglect stretching and mobility movements to reduce stiffness.

Another point is - don't forget your immune system too. Rigorous exercise (running, swimming, lifting weights, etc) without sufficient rest  and proper food can be detrimental to your immune system, and make you more susceptible to colds, etc.