The stock seat can be improved if you remove the stock cover and upholster it in leather. You can buy all kinds of leather/suede that is suitable to recover your seat in any color, thickness and roughness (even perforated).
Buy the leather and have a professional do it if you're not handy. All that's needed is some contact cement and scissors. I've tried suede and found it to be too grabby which made it difficult to move around easily but it certainly prevents sliding forward under deceleration. A better solution is a very soft smooth leather. I reupholstered a Corbin seat in deerskin and it is truly a luxury.