This is interesting.. The bag I use the most would be my Speedy or Neverfull but my favourite that I enjoy carrying and makes me feel special is my Alma BB in Epi.
Must it be a handbag? As an organizational freak, and someone who has always loved planners, my MM agenda was the most ridiculous splurge ever. And I never go a day without it. And I have never regretted it for a second.