I recommend the Gripster. I've found the collet on the standard type grips can often loosen itself in the course of normal knife handling. Since the Gripster tightens at the back, it avoids this issue completely.
The con of the Gripster is the hollow barrel feels relatively insubstantial in the hand, and that can feel odd. Generally speaking, I've found that the normal-style all metal handles have a superior feel and build quality, but the Gripster is superior in actual operation.
Avoid off-brand versions of this handle type like the plague though, as the barrel will not always be centered relative to the blade/collet, and sometimes will be made of plastic that flexes.