Holtz was a very, very, clever man.
He was no doubt a witch hunter in his time and if anyone knows anything about European witch hunters it's that they were some of the greediest people on the planet in their day - they'd often rob the spoils of their "witches" to fund their themselves, and I think that the watchers council was probably born out of the remnants of at least one group of witch hunters.
Either that or Wolfram and Hart initially started the council by giving them the resources (IE the books and stuff) to learn about demons, vamps, magick, etc etc before the council realised they were on the 'other' side and split from them (personal opinion here by the way, so please don't shoot me down if I'm wrong about it.)
I don't believe however that Holtz was that kind of witch hunter though, as it's been previously stated that he lived in a modest dwelling with his family, and family meant everything to the man. I agree with the statement that he was probably the best Big Bad in Angel - as he was Angel's own personal Big Bad and when he stated that his revenge would be total (or what-ever he said, I don't exactly recall the exact words) he was counting on Connor to be the instrument of that revenge by programming, if you take the metaphor, to be the instrument of that revenge. It's just a shame that he was unable to stop Connor from bonding with Angel and the crew; Connor's feelings toward them made the betrayal that should have been Holtz's revenge that much harder so the plan was changed to suit his (Holtz) purposes.
He did have to change his plans several times, again - this has been mentioned, but that's what the man was good at - manipulating others to do his bidding whilst keeping his hands relatively clean, although, as we know, he could mix it up with the best of them when he had to.
Holtz was the main man in his day, and even when brought forward two centuries, he still had the where-for-all to know how to do his job even though his surroundings had changed beyond his wildest imagination.