ESI's far and away the best grip I have ever used, comfort and weight of foam grips but with the stay put properties of lock on's (just a bit of windoline in the when putting them on and leave for 24 hours) without having to have horrible bits of metal digging into your hands.
It's little wonder that most xc pro's use them, no matter who sponsors them.
They do cost a little bit more than normal grips, but only a few £'s and last a reasonable time, doubt you will want to use anything else after using these.