Crocheting: 'knife' grip vs 'pen' grip When crocheting, there are 2 grips for holding the hook: like a knife or like a pen. The choice is - of course - a matter of what you've been taught and what you prefer, but can anything in general be said about the (dis)advantages of both grips? 
For instance, 


is any grip better for your finger joints and wrist, 
does it help to crochet faster, 
is it easier when crocheting larger (heavier) projects, 
does it allow you to switch yarns more easily or anything else that occasionally needs to be done during crocheting, etc.


Also, if there is another way to hold the hook, please don't hesitate to mention it.
Practicing with both common grips is a good strategy.

While you will naturally develop a preferred grip for most projects, having a variety of approaches you are functional with will make a much broader range of thread weights and project weights possible for you to accomplish with some ease.

Also being able to alternate approaches will go a long way toward reliving tiredness and joint strain on big projects.

Short answer:  BOTH in combination are better than either alone. 

It sometimes helps to wind a small scrap yarn ball around your hook that will fit comfortably into the V formed by your thumb and index finger metacarpal bones. There are commercially available hook designs that accomplish similar aids.