I've been quilting for a year and from my experience so far, it totally depends on what quilts you like to make.
I started out buying fat quarters, but found they tend to be too small for what I like to do with a color. So I started buying yardage - and am finding that more than a yard is usually too much for my uses. If I need more for a border or backing fabric, I prefer to buy it as needed to make sure I'm happy with the match. Sooo.... at the moment I'd tend to buy a yard or so.
I've always gone for the fabrics I loved, and that turns out to have been a good decision. There are a few in my stash that I bought because I thought they'd "go with everything" (neutrals...) and hey - I'm not using them.
I'm just not a traditional quilter and not big on neutrals. I've now sorted those "sensible-but-uninspiring" (for me) fabrics into their own stack, and might use them for dyeing and painting on once I get around to that.
So... sorry for the novel, it's just in case any of this helps you think! :D What I'd most like to recommend is, trust yourself. Buy what you love, experiment, find out what's best for how you like to create.