Aveline gets an exclusive passive talent for knockdown immunity, which is a HUGE benefit when fighting big ass bosses, which tend to knockdown characters with every hit.  Once knocked down, it's hard to get back up again. Stonewall helps of course, but due to the warrior's stamina mechanics (stamina recovery on killing blows), there just ain't enough reliable stamina to go around.
 
Even Hawke can't specc knockdown immunity. Does this make Aveline the only viable tank in the game? Especially when playing NIghtmare, how much easier many things would be running with Aveline and her knockdown immunity...

There are items that grant stun and knockback immunity.  A few rings I've seen at the Black Emporium.

Not enough stamina?   I find the Battlemaster tree really great for any tank and it has alot of stamina regeneration talents.  don't have to spec many points to get Bolster, which is free stamina and spammable.

My Fenris had a ton of strength so he almost never knocked over. And once I threw a valiant enchantment on everyone's armor, most people stopped falling over.

Not really, but she is a damn good tank. Sadly her constant disapproval to my actions means that I rarely use her.

Aveline is a beast. 

" My Fenris had a ton of strength so he almost never knocked over. And once I threw a valiant enchantment on everyone's armor, most people stopped falling over. "

@Cataphract1014

" There are items that grant stun and knockback immunity.  A few rings I've seen at the Black Emporium. "

" Would be quite a hassle to run a group setup with 2 warriors on Insanity. "

" @Seppli said:

" Would be quite a hassle to run a group setup with 2 warriors on Insanity. "

I'd imagine that having a 2H DPS warrior able to offtank in a pinch when there are too many mobs around and your squishies are in trouble would actually make it easier. Then again I'm playing it on Normal so what do I know. "

There's a great part in one of the final battles where the boss starts to monologue, and so stuns your entire party (and their minions) to stop interference. Except that Aveline has stun immunity, so she could still attack and do damage COMPLETELY unopposed.

" There's a great part in one of the final battles where the boss starts to monologue, and so stuns your entire party (and their minions) to stop interference. Except that Aveline has stun immunity, so she could still attack and do damage COMPLETELY unopposed. "

Stun and Knockback are not equivalents to Knockdown.
 
A Knockdown occurs when your character is sent flying to the ground.

" Stun and Knockback are not equivalents to Knockdown.  A Knockdown occurs when your character is sent flying to the ground. "

" Not really, but she is a damn good tank. Sadly her constant disapproval to my actions means that I rarely use her. "

"Aveline is a beast.  "

Mage Hawke, Anders, Avaline, Fenris is all you need for an unbeatable 4! We took down the Dragon in bone pit easily.