Any type of equipment will work for a certain amount of time. If you were to get a bowflex use it for 1-2 months, then switch to free weights. This way your body is always thrown off and doesn't adapt to certain movements, weights, range of motions, etc. Your body will always be off balance so to speak.
As long as you are taking in to account your nutrition, recuperation, and supplementation you will grow. This is what is more important IMO:
1 Diet- Important as this really makes or breaks your progress
2 Training- This is the stimuli for you body to make changes
3 Recuperation- Without this your muscles won't grow and you'll become overtrained. So get your required sleep and rest!
4. Supplements- This is your Creatine, NO2, AAS, anything in that realm.
Having these things working together will have an overall positive synergistic effect on your body. And this includes whether you use bow-flex, free weights, Total gym, etc.
All posts are for entertainment purposes only, and are theoretical. I do not use, or condone the use of AAS.