Definitely barnsby grip pads are ace! They are expensive but really work and look smart and wear well. I have used mine constantly since about January ish and it still looks good and works a dream.
I have a gel grip thing but it annoys me that you can only use it twice before it loses all grippiness.
I also have a limpet pad type one which works quite well but just doesn't look that smart.
I have the Ecogold jump one for my jump saddle but it isn't quite the right cut and have to say for the money (it was over £90) I have been disappointed with it.
I have the acavallo gel pad one combined with a dressage square - only used it twice since I got it due to events being cancelled and trying to keep it for good but been impressed with it so far
As usual I'll disagree and say that your saddle isn't quite a perfect fit. In four years fitting very wide tricky horses I've yet to need a sticky pad to keep a saddle in place and really don't like them. Much better to seek out a second opinion and get your saddle fitting better. How would you like sticky pads against your skin to keep shoes on that were too big? Wouldn't you prefer shoes that fitted? (closest analogy I can think of)
I agree - I'm not the OP but unfortunately my saddle fitter is taking over a month to get my new saddle so I have to do my best with a borrowed one in the meantime. I nearly died when she told me how long it would be - I think they have to hunt the cow on foot to get the leather.