Firstly, i'm not a math genius so I don't have much to back up my statements as far as that goes. My instincts, and you fine people on tankspot are what I rely upon. It seems that a lot of our threat is currently based upon attack power and block value. BV helps with general threat (shield slams and damage shield), Thunderclap and Shockwave both are based upon attack power as well. Blizzard has already stated that they want all classes to be able to DPS (tanks now included). This leaves me in a predicament as to what are my main items to go for when choosing gear. Strength seems to be more useful than ever because it covers both AP and BV. Dodge, and effective health have always been great to gear for. The problem is we have too many options in gear now, and IMO not enough answers. There is obviously a direction blizzard is taking us, with regards to how they've built the talent trees. What do you think that direction is?
Defense (to uncrittable) > Expertise > Hit = Strength > BV > Dodge > Parry
is the way I tend to define my priorities right now. However, it's all dependant on what you're currently lacking. If you lack survivability, get more defense (it's better than dodge now because of DR).
Another thing to consider is that the change in gearing philosophy and the current itemization we're seeing make it pretty obvious which pieces are superior pieces. I'm 79 right now, and I've found a TON of gear with Defense and Expertise on it. I love it. Your first priority when gearing, at least at 80, should be to reach uncrittable status. Once you have that, you can take some more time to analyze how well you're surviving and how easily your healers can keep you up. If they're fine, expertise and strength are the way to go. If not, more defense and more stam.