I've had some quite good results using the P21s GEPC topped with a couple of coats of Wolfgang sealant.
I think these two go together well. I have also went straight to P21S carnauba wax.
If money / time / effort is no problem my ideal would be GEPC, 2 x Wolfgang and then topped with Pinnacle Souveran. That is my favourtie combo of the moment - regardless of the colour of car - it just looks great!!