I could talk pear rootstocks the next 10 years and there are pros and cons to each ranging from Cotton Easter, Aronia, quince, Hawthorne, ohxf, callery , harbin ,etc… The size of fruit , tree , graft compatibility, years to bear fruit all make a difference. My favorite today is Pyrus betulaefolia or Pyrus calleryana until I age then I will post about being a big dummy when I try and pick pears!