I know there are threads out there like this already, but with 3.05 out now and tweaks made to abilities and what not I just want to know:

Which tank would be best to level for someone interested in tanking but has never done so?

At the moment both my Gladiator and Marauder are below level 20 and then, of course, Dark Knight is at level 30. I know regardless of which one I have to level them all some for cross class abilities. Thoughts?