Here's a quick and dirty comparison based on information the Theoryjerks have crafted so far. If you have 2500...

Critical Hit - Your DPS should increase by approximately 9.3%
Direct Hit - Your DPS should increase by approximately 8.8%
Determination - Your DPS should increase by approximately 8.5%
Tenacity - Your DPS should increase by approximately 6.4%
Skill Speed - Not quite that easy, unfortunately, as it highly depends on what Tank you're thinking about.

As you can see, Tenacity falls behind when it comes to damage when compared to the more specialized damage increasers. That's because it reduces the damage you take by the same amount. It will never beat the other stats in raw damage due to this extra bonus but, as you can see, it's not far enough behind that having some will cripple your damage output. The days of the "Tank Stat" contributing 0 DPS are long behind us, fortunately.