I love my TRX. I can do Pilates, strengthening, stretching or cardio at so many various levels. It reveals weakness that so many other things do not. Multi-planar is the way to workout! I use it with my 87 yr old client and my kids who are 4 and 7 love it too. So versatile! Free weights or body weight resistance is next.
Beyond body weight exercises, my choice is dumbbells to start with. Easy to learn, overload and progress, infinite variety, found almost anywhere, and (relatively) inexpensive for clients just starting out at home.
From there, a plethora of fitness accessories including but not limited to kettle bells, sand bells, sandbags, TRX, medicine balls, tires, water jugs, battle ropes, and other similar equipment that allows for natural, real-life, functional and dynamic exercise movements.
This answer depends on the client/patient you are training. There are many biomechanical, physiological considerations before selecting a piece of resistance training equipment as well as the load, intensity, duration, etc. There should not be any “equipment” of choice as far as to which is best because each are unique in their own ways which will tax the body differently and impose different benefits, whether they are muscular, neural, skeletal..etc. As far as “functional equipment” I think that is a farfetched statement. What is functional equipment. Anything that will enhance your ability to perform something (the definition of functional) is functional. therefore, any exercise will be functional because it should help in many different areas!
Fuel the Movement,