Mine is the Fossil Grant one I had a few years ago. It was so pretty and soft and useful. Just the right size. The best thing was it was corduroy, and leather, and had little flowers on it.
I actually stalked another mum because she had one and I couldn't see the brand name on it and it was so lovely. Eventually managed to google it and bought one in a different colour.
Then it was a bit embarrassing because she wore hers every day and I felt like I had done something awful by buying the same one. I tried to leave it in the car a lot! 
We weren't close at the time but since then we kind of got on really well and I stopped using my bag eventually as it fell apart, as did she, and I never admitted I'd copied her though I think she probably guessed.
Anyway. That's my all time favourite and I just managed to find another on ebay in a fit of nostalgia for about £15 
(My old one was dark red but still!)
What's your best ever bag that you remember with fondness and have never managed to better?