Who do you think had the worse character between Himmler and Heydrich?
Uh, that's like trying to decide whether you'd rather die from cholera or the plague. They're not the same, but both are horrible.
I think the main difference is that Himmler considered himself to be a 'visionary'. By that I mean he brought in his own (poorly articulated and contradictory) ideas about what Nazism was about...though he could be very flexible when it suited his political purposes. Heydrich was no less of a Nazi fanatic than Himmler, who was basically his mentor. However, he was more comfortable as a man of action who turns abstract ideas into a (horrifying) reality.
On a personal level, Heydrich was ironically a more difficult boss to work for than Himmler. Basically, Himmler viewed himself as the 'patriarch' of the 'SS community of clans', and basically behaved like an overbearing father/schoolmaster, mixing punishment with fatherly praise. This is also reflected in his meddling in the private lives of his minions so that it reflected what he considered to be the 'SS ideal'. He was polite and proper in his dealings with his subordinates and Party colleagues, though kind of superficial and overly formulaic. Longerich postulates that he had an attachment disorder since he seems to have trouble maintaining relationships where he wasn't either the subordinate or the master. While not personally charismatic, he had a knack for picking subordinates who were capable at achieving the ends he wanted, but also had messed up in their past in some manner and thus needed a second chance. Globocnik, Eicke, and Heydrich are good examples.
By contrast, Heydrich seems to have had a temper and been quite impulsive, contrary to the popular image of him being an unemotional human calculator. We must obviously take the post-war testimonies of his former subordinates with a big grain of salt, but overall he comes across as very controlling and suspicious. That was one of the reasons for his falling out with Best, who'd been one of his closest collaborators during the '30s. Overall, he seems like the kind of boss subordinates would respect and to an extent admire, but not love. Like many members of the 'war youth generation', he had a complex about not having gotten the chance to fight in WW1 and earn 'martial glory', which is why he decided to play Luftwaffe pilot during WW2.
Also mildly amusing anecdote: When Himmler introduced Kaltenbrunner to the RSHA section heads as their new boss, he had nice things to say about him. Which is to be expected since Kaltenbrunner seems to have looked up to him at least back then and Himmler regarded him as a loyal protege. However, he spent most of said speech going on and on about the good times he and Heydrich had had together and what a nice guy the first RSHA chief had been. I can imagine that Kaltenbrunner felt really awkward during that part since his relations with Heydrich had been pretty bad.
I've seen lots of your knowledgeable posts around. What sort of project was it?
Thank you. Until last year I worked in a research project called 'The Persecution and Murder of the European Jews by Nazi Germany, 1933 - 1945'. It's a joint project between the Institute for Contemporary History (a German research institute), the University of Freiburg and the German Federal Archives, in cooperation with Yad Vashem. I'd be remiss if I didn't mention that my job was low-level, but I was involved in the creation of several volumes. Basically I helped with research and quality control.
Basically, the goal is to produce a multi-volume source edition covering both Germany as well as the countries that were occupied during the war. Each volume consists of several hundred primary source documents from the perspective of perpetrators, victims and bystanders. The German language edition was completed some time ago, while the English version is still being worked on. I think they're working on one of the volumes about Poland at the moment.
