legropes
You're not tying the leash around your fins are ya? That'll wear it out. As for brands I've had a kommunity leash for a few years that's lasted pretty well.
Brian,
Over the years I've gone through all the brands and it's been my experience that none of them are better than the others. I'd probably snap around 3-4 per year, depending on travels, and these days I shop for them purely on price. That is, I get the cheaper ones (within reason) because I don't believe that the expensive ones are likely to last any longer.
On Shaun's point: keep your receipts!
Sheesh, I've snapped two leg ropes in a matter of weeks in not very sizeable swell... Can anyone suggest a good, reliable leash brand? My FCS leash broke at the little metal swivel and my Dakine leash literally snapped.