In my time MOCing, I've changed a lot. I've gone through different phases. At one point I hated the hand peices they introduced in the glatorian series. At another I thought it was herecy to mix ccbs with bionicle parts. But something I've learned is that generally speaking, you want a good system parts to technic parts ratio. Typically, my MOCs look better the fewer ball joints and armor plates they have. For instance, here's a couple of MOCs I'm getting ready to upload to the boards (the one on the right isn't finished yet.)
Personally, I'm happier with the one on the right so far than I am with the one on the left, primarily because it's extremely difficult to go beyond basic only using bionicle/ccbs parts. You can do some creative things if you have an absolute MOTHERLOAD of parts or you buy stuff on bricklink all the time, but I don't have that option, and neither do a lot of beginners and amateurs.