1) I think you should play both DRK and WAR -- rack up a good amount of playtime with both of these at level 60. WAR certainly deals more damage than DRK when played properly. However, DRK has a ridiculous kit of defensive cooldowns which allows the DRK to thrive in both magic AND physical-damage-heavy fights whereas WAR is at a significant disadvantage when faced with lots of magic damage. Nevertheless, regardless of how much physical or magical damage is being dished out in a fight, both DRK and WAR have the ability to tank any fight just fine. DRK deals less damage, of course. Other than that, it all depends on your playstyle.
I have played both DRK and WAR in Alexander Savage and I can say that I prefer DRK because to me, it's much easier to max out my dps with DRK than it is on a WAR. No matter what tank I play, I always try to max out dps without placing too much strain on the healers, but the problem is that in order to max out dps on a WAR, you must very effectively plan out when you'll use Berserk. I'm not the best at planning, so WAR does not suit my playstyle.
2) Secondary stat priority is Crit > Det > Skill Speed for all tanks. For primary stats, you'll want to max out your Vitality. Vit and Str both give you the same amount of attack power per point. Use this https://docs.google.com/spreadsheets...YcA/edit#gid=0 to calculate how much attack damage you'll get from any one piece of equipment.
3) My idea of the best in-game tank has nothing at all to do with the class (DRK, PLD, WAR) being played. In my raid group, I play DRK/WAR with DRK as my main. My co-tank plays PLD/WAR with PLD as his main. I consider my co-tank to be ridiculously good regardless of what class of tank he plays because he pays attention in raid, has great raid awareness, barely makes mistakes, and he constantly looks for ways to improve his game.
4) The post limit can be exceeded by editing your post and adding more to your post.
Sorry if my reply is not so coherent or easy to read... I'm sleepy lol.