I think there's a lack of good feat competition, which is unfortunate.
I know when I was looking at feats for my Dwarven Hybrid Cleric, I would totally grab Polearm Gambit, Uncanny Dodge, Deadly Axe, Dwarven Durability, and probably something that wasn't the defense feats.
With my Human Infernal Warlock, I'd totally be grabbing those Defense feats, but that's largely due to lack of options. =/ Maybe not in the Paragon Tier... but in the Epic Tier? Definitely.
I do really like Toughness... I think it's a good pick. In order for +1 AC to compare, you need to have 100 AC-targetting damage come at you in a fight. Modify that value by 25 (since each surge is +1.25) for each surge you use in a fight.
As for Durability, I guess it depends on the style of game you run. Durability seems like it could be good, depending on your class and the DM's encounter style, but I'd hardly classify it as a must have.