I am going to use a tank scale related to the number of Justicars in Riverside Province.
Warrior/Monk, as you can see in my profile, it is my main character. It can solo almost ANYTHING while doing some beautiful damage. I can kill around 15 - 20 Justicars at a time, in around 4 minutes or so without even breaking a sweat. So I come out with full health, and during the fight I have constant over 90% health. I can solo some higher leveled missions, and I can solo Lornar's Pass.
Smiting Warrior/Monk that can tank better than my build above, yet kill everything in under 2 minutes. Think AoE, think Spirit, think Healing. I can kill around 20 - 25 Justicars in 2 minutes with a constant over 70% health.
Ranger/Monk that can tank better than both builds above (getting the pattern? :P ), but in terms of AoE damage it is slighty limited. After all... I can only hit 5 targets at a time. U_U 20 - 25 Justicars, constant over 90% health, takes around 7 minutes to kill them all. Lornar's Pass is even easier.
Monk/Elementalist that can tank almost as well as the Ranger/Monk, but doing RIDICULOUS AMOUNTS OF DAMAGE. Haven't tried 20+ Justicars because that seemed unrealistic even in my insane mind.

Elementalist/Monk, tanked as well as my first build, doing around the same damage as the build above. I actually timed this one, 23 Justicars in 57 seconds. Gotta love my brain.
And finally, for those whining about Necro/Warriors not being able to tank as well as a W/Mo.
N/W, tanked the best out of all my builds. Basically I lured as MANY Justicars as I could find, must've been about 40+, and I just stood there and tanked. No Mark of Pain or any damage, I just stood there and tanked until I got bored. If I actually wanted to do some damage... heh.

Thankyou for your time, again, if you shout BS and attempt to flame me, go ahead and waste your time. :P
Till next time,
Rusty.