The part about Geneva being better on poorly drained soils.
You are probably right. The Geneva rootstock table does say they are tolerant of Phytophthora crown and root rots. http://www.ctl.cornell.edu/plants/GENEVA-Apple-Rootstocks-Comparison-Chart.pdf
106 is well know to suffer collar rot issues in wet soils, but I believe it is still the most productive rootstock in its vigor level (in soils with good drainage), although I don’t really keep up with rootstocks not readily available. I don’t buy my trees from Cummins and they seem the only reliable source for the Cornell rootstocks.
111 is my go to for a reliable and available rootstock.