Which is better? Sydney or Melbourne? In terms of job vacancies and cost of living.?

I will be soon moving to Australia and initially I was planning to move to Sydney. But I 've started to hear some "horror stories" regarding the cost of living expenses over there. Compared to Sydney, is the overall living expenses in Melbourne cheaper?(If so by how much?). And does Sydney area have lot more jobs compared to Melbourne. I'm really thinking into the balance between cost of living and job vacancies within these two regions in Australia.