Bob Opponent Bag What's The Efficiency Of These Types Of Martial Arts Training?

What's the efficiency of these types of martial arts training? - bob opponent bag

I am a man JKD / Muay Thai Training (non-members). Do you have difficulties to decide. Which of these would be better if I start in mid-section, straight shots / shots low and high?
1) Free-Standing Punching Bag (hanging is not an option)
2) the opponents bag (or Bob Stock Exchange)
3) Any other method
If you have suggestions, feel free to leave. We examined some of these products, I just need more opinions.