I first try to get queens from Mike Palmer Failing that I will use queens from any source that has some. This year I have 10 nucs for wintering with New World Carniolans.
I made 6 walk away splits in spring and they all requeened themselves successfully.
I have had three hives swarm and all have requeened successfully.
Operationally I am moving towards letting the bees requeen themselves as much as I can. This is why I call them mutts. At some point the natural mating process combines genes from at least 8 if not more drones of unknown lineage.
But seriously, I cannot say one has done better than the other. I have tried Russians,Italians,VSH,Carniolan etc///. Managing mite load going into the winter seems to play a huge part in winter success.