There are several good systems. I'm a certified BG fitter, as well as certified with the retul system. You're familiar with the BG system, as you've already been through it.
Retul is a system which uses power measurement and body position sensors on a 3 dimensional wire frame (virtual) reproduction of your bike and body. It allows an experienced fit specialist to see the skeletal body position without the intervening tissue interfering with the process. The power measurement is individualized to each foot, which means that efficiency can be improved and equalized, and you can see in real time how a body position change affects your efficiency on the bike.
In my opinion, they are both good fits, performed by a skilled bike fitter. A skilled fitter can be defined 3 ways:
First, your fitter should ride a bike. Now, experienced fitters are often the older guys in a shop, so they may not be fast or aggressive riders. They may even be fat. But they still need to ride, to be able to feel the way new bike styles and fit ideas affect the way a fit should be done.
The fitter needs to be experienced at bike fit. Preferably, years of experience. Learning to properly fit a bike is a time intensive process. It is best accomplished by an apprenticeship with an older, experienced fitter, in combination with classroom education on new tools and techniques. It is ok to be fit by someone who is learning, but it will take more time and you should expect more trial and error in the process.
The fitter needs to be willing and able to examine the method of fit he is using and modify it to fit the needs of the rider. Meaning, a skilled and experienced time trialist needs a very different body position than a first time roadie looking to do a century in 6 months. A fit must take into account the fitness, experience, and intent of the rider. A fitter who fits everyone the same way is unlikely to do well for all of his or her clients.
So, to get back to the original question, there are many good fit systems, but what works best for you will depend on your intent, experience riding, and your fitness.
The BG fit is a great option for riders who are more interested in comfort than in efficiency. There is a balance point where comfort and efficiency meet up. That is what a well performed BG fit will find. But, there is a point where a racer, who is generally more interested in efficiency and power than in comfort.
There is a certain amount of pain and suffering that is expected of a rider who is looking to maximize performance, which will come at the price of a loss of comfort. The Retul fit does a great job of maximizing performance, bu the "comfort" zone it looks for is peak performance without actual damage to the body.
Both fit styles in the hands of an experienced fitter can be tuned to the rider. I find that quite often, though, there is bit of "I drank the Kool-Aid" mentality with fitters who have the classroom training, but not the flexibility or possibly the experience to recognize that every fit must be individualized to the rider.
So, I guess, what I'm saying is it is worth checking out other styles of fit, but it should be a style and a fitter which fit with your intent on the bike.
Make sense?
