Usual way of killing USB cables is either treading on the connectors, or supporting the weight of the device by the cable where it exits the strain relief because someone thought it was a good idea to put the charging socket on the bottom edge.
I find the ones that live on my desk for plugging things into the computer last approximately forever. The one in the bedroom that charges my tablet is fine if you don't leave the trailing plug where it'll get trodden on. The ones I carry around, particularly those used when camping, tend to die much more rapidly, because of weight-bearing and bend-radius abuse.
I've found that right (or left) angled connectors seem to help somewhat. Startech ones are okay (they also do a handy looking one with a hammerhead plug with both mini and micro USB on it, but those are made of cheese).
Apple proprietary connectors just add to the fun...