Are there any chiefs-of-staff who stand out as exemplary at the job? What about awful? How much does quality of White House personnel affect legislative outcomes?Exemplary? I don't know...I think Jim Baker for Reagan did well; the Clinton chiefs-of-staff after McLarty were generally a good lot; and, yeah, I think Rahm Emanuel did a good job -- in part, by wisely leaving before he went all Sununu. Howard Baker probably goes on this list, too. Maybe Sherman Adams?
Awful? Well, I think Bob Haldeman sort of goes in a category all his own as a major disaster: if you and half your staff go to jail and the president resigns to avoid impeachment and conviction, that's not real good.
Beyond that, Hamilton Jordan was a disaster, as were Donald Regan and McLarty. Andy Card, maybe? The presidency was certainly a disaster while he was there, but he was widely seen as having far less influence than the usual Chief of Staff.
How does it affect legislative outcomes? Well, it has to be a subset of how the presidency in general affects legislative outcomes, with the latter being often overrated. Still, while all such evaluations have to be put into the context of both the president (as Brad DeLong always likes to say, the cossacks work for the czar) and how the votes line up on the Hill, it seems reasonable to say that Jordan contributed some to Carter's failures in Congress, while Baker contributed to Reagan's successes. Or, to put it another way: Bill Clinton's first two years would probably have been more productive if Leon Panetta had started out as Chief of Staff -- but then again Clinton hadn't yet learned that, so it wasn't just some sort of random fluke that Clinton had McLarty and then replaced him with Panetta. How to attribute responsibility in such situations is difficult!