I go to the one LQS because I absolutely love her shop and she's a gem. She has the most amazing quilts on display too.
I go to another one a bit further away because it's a destination store. You go there just to go there. Even the dog greets you. The store is in an antique home and every nook and cranny has fabric and notions. It's an amazing experience and "Shirley" is an encyclopedia of quilting knowledge. We go with a group for a road trip and then go out for lunch :) which is always fun!
The third shop I do attend often is an hour's drive away but she has the cutest fabrics, I always find something new there.
My local fabric chain store does however get most of my fabric purchases just because of their prices. And their sales. I can count on a good sale every month - so that's when I stock up.
I've only started using online stores, the prices are good, but I'm always nervous about the quality of the fabric because I don't get to 'pet' it first.