There is only a 1-3 degree difference between the most expensive pastes and average pastes. You have to get into exotic stuff like liquid metal to get better results. Or de-lidding and lapping.
Also depends on the CPU cooler. Very shiny nickel plated coolers need a more fluid paste. Rougher bottomed coolers, and those with exposed heatpipes, should rely on thicker compounds to fill in the large gaps. Arctic MX-4 is a nice mix between the two extremes.