I'm having a hard time picking between which 65xx+ head is best from that. When going through your monitors it was easily the 6534+, however on my earphones at work they aren't as distinctly different. Maybe my monitors at home will tell a different story.
There are actually parts of the Ultra I like over the other two though. It's slightly muddier, but it has a slight bit more chunk to it too. Annoyingly enough, add a tubescreamer and that'll probably take the differences away (good in making it more defined, less good in taking the bit I like more about it!).
The combo is impressive for the price mind you. While it wasn't a huge amount less than my Ultra (£300), mine is much older and hence you expect a bit lower price. The combo in a room on it's own sounds great and up against other amps too. Perfect practice room and small-to-medium gig amps it seems. It did seem to lose some definition once it got to the volumes that the other three were at, but thats all in the power tube saturation I reckon.