If I could study with any two living historical Jesus scholars, I'd choose E.P. Sanders and Gerd Theissen.
Sanders may well be the greatest living New Testament scholar. His research marks seachanges for both Jesus studies and Paul studies. It is difficult to imagine what contemporary New Testament studies would look like without him.
No less important is Gerd Theissen. Theissen's Soziologie der Jesusbewegung was published the same year as Sanders' Paul and Palestinian Judaism (1977) and argued that Christianity began as a Jewish renewal movement. Moreover, this argument was leveled in a context wherein such a statement was highly disputed. While the "Jesus as Jew" era in Jesus studies is often credited to others, Theissen's work (translated as Sociology of Early Palestinian Christianity) has never received due credit. Indeed, his Wikipedia entry devotes only one line to this book: "His Sociology of early Palestinian Christianity (1978) is useful for interpreting intertestamental literature." This is absurdly faint praise for a groundbreaking book. Not only does Theissen anticipate the next forty years of historical Jesus research, he demonstrates how interdisciplinary use of sociology ought to look. I also firmly believe that his analysis of rural attitudes versus urban attitudes within first-century Judaism has not yet been fully appreciated by historical Jesus scholars. I suppose I also admire the gumption it takes to write for the popular level in ways that grind against the grain of most ivory tower folks.
Oddly, I have never met either one of these scholars face to face.
p.s. to see the full results from the Jesus Blog readers, see here.