Personally, I use both, although the original bionicle system is atm more preferable than ccbs as I don't want to take apart my new bonkles, and I only got one ccbs set previously (voltix).
I see ccbs as a way to create much more human-like builds, but at the same time it has the potential to create creatures. The original system makes HUMANOID forms, but they often end up looking less realistic (not saying that is a bad thing). For example, my self moc (which I need to post) includes mainly original system parts including parts from hf 1.0 (think von nebula) but uses some ccbs parts too.
I personally find that ccbs is a lot easier to pose when you want a more human character (such as the protectors) but when using the older system you CAN pose the characters well, but they can often be quite hard to find a decent pose which looks good from all angles. You could say the same about ccbs, but if you know how to pose either, they are both good for posing.
I find that ccbs is a lot more compatible in any build than the old system is. I find that ccbs fits in well in old system based builds, whereas old system is more out of place in ccbs based builds.
Overall, I believe that they are both equal. They both have pros and cons. Before bonkle 2015 I would say, for nostalgia's sake, the old system was better. But now holding poj in my hand, I can see how well balanced both systems really are.
But this is just my opinion and I respect your own opinions whether they are similar to mine or not. How do you use both systems? Do you prefer one over the other, or do you appreciate both?