I use Grip-puppies and I like them.
On a BMW K100RT I had there was excruciating vibration through the bars at around 100 kph and it was suggested to me that I fill the handlebars with lead shot, available, I was told, from a fishing tackle shop. Remove the right-hand bar end, with the bike on its side stand and using a funnel, fill away. Could probably blow it in with an air hose if needed.
I never got around to it - sold the bike - so I can't vouch for its efficacy.