Staying power is important because I don't want chase friends. I wan to love my bag as long as possible.
BUT! If I tire of it I want to be able to recoup funds for another purchase. So resale value is critical.
This is my main criteria. Like my clothes, I want bags that are timeless-- that live beyond a season. Then again, it's all subjective. It really is about what you like. Now whenever I purchase a bag, I do keep that in mind. My tastes have changed drastically in the past 20+ years, so I shy away from bags I know I'll only have a fleeting love affair with.