Data clearly shows that purely doing cardio will produce a greater outcome of Losing weight than doing weight training alone, or weight training + cardio mix...
However - weight loss is NOT fat loss. When you look in the mirror, you're hoping to see the best possible figure right?
That is a factor of body composition, not your overall weight. It is your ratio of lean mass to fat mass that you should be concerned about.
So while doing cardio alone will produce greater weight loss, it does not actually produce a greater fat loss than weight training and cardio combined. The extra weight loss is explained by MUSCLE LOSS!
If fat loss is what you're after, always create a strength training program as your foundation. Once that is established and calories are in check, it wouldn't be unreasonable to add some cardio into the mix.