My D3 feels as though it were made for me. The grip and the controls are just right. The D800/D810 feel fine too. The D750 feels just that little bit too small. You sound to be in the same boat.
Between the D3 and the D3S, the latter offers less noise at higher ISO and a feature that shakes dust off the filter in front of the sensor. If you do not mind the slightly higher price then it would be my recommendation. That said, I am in no hurry to give up my D3. It is a better camera than I am a photographer :)