I don't use just 1 but The best ones I've used are
Megs D156
Megs Last touch QD
CG V7 hybrid
DG aqua wax
FK 425
WG QD spray
I have gotten away from using QDs and started using Megs D156 and CGV7 more just because they lay down more protection. I also go over the dry car with them right after for that full, even, undiluted coat of protection.