As said above, pet durability doesn't affect the passive boost.
A tip though, I'd say think carefully about which one you need. For example, the 10% agility pets may be good for someone with a pure evasion or atk spd build on a specific class, but they won't really benefit anyone else all that much. I went for the Magic Persian Cat (+3% elemental resists) because it increases resistances for all classes, which can be helpful vs a lot of annoying bosses (especially in higher level dungeons, from Century upwards really). Same with the crit pets really, it doesn't benefit all your classes as well as other pets.
Hope that helps ^^