Someone brought up a very good point recently and I wanted to share it with you. While people are always searching for the perfect training system they seem to miss one very important point; what makes them happy. If you do something that you like and something that makes you happy, you are more likely to put greater effort into it and thus get better results.
For example, I like to train heavy on big exercises. If someone said I should train lighter on isolation exercises because I would get way better results, I would ignore the advice because I would hate doing it. If I am unhappy when I train, my results will suffer. I would rather quit training than start doing leg extensions for 20 reps.
Some people like body building splits better than any other split. If I trained someone like this and tried to force them to do full body workouts, which they hated, their results would suffer. We would both be miserable and they would get nowhere.
If you love doing body part splits and hate all other options, stick with body part splits; it will probably yield you the greatest results.
Some people like extremely overcomplicated, planned out, scientific training programs. Others like the most basic, simple plan they can find. The science guys hate simple programs because they over think everything and believe that if they are not counting rep speed and measuring angles with a protractor during their training, they are not achieving optimal results.
The "keep it simple" guys hate overcomplicated programs and don't like thinking that much during training. Training is a hobby that they love and a release from the stress of every day life. If they have to think everything out and break out the Pythagorean Theorem to plan every set of their workouts, they will be miserable. These kind of guys like to go in and lift; that's it.
There is nothing wrong with any of these approaches. While I prefer full body workouts or upper/lower splits to body part splits, and simple workouts to complex science projects, it doesn't mean that this is the optimal approach for you.
Being happy in what you are doing is a very important factor that can not be overlooked.
There have been times in the past where I have designed a program for a client and after seeing their dissatisfaction with it after the first day, have completely scrapped it and started over with something completely different.
It's a universal law in life; do what you love and the results and success will follow.
So what's the best way to train?
Whatever makes you happy...