I think I would be happy only having TZ... but also having owned WOZ for coming up on a year now and not even being close to tired of it, going to have to go with WOZ, for the same reason as those going for TZ. Super deep rules and lots of ways to play/approach it.
Also it can be setup to be friendly to new players and has lower level objectives anyone can reach in addition to all the deeper modes.
Further, its simply a bueatiful game to look at with a spectacular light show and fantastic audio.