To be perfectly honest, both work well in different ways. Maybe the question should be what are your goals? If the answer is, to be muscular and ripped then weightlifting will take precedence. If you want to lose weight without bulking up or building noticeably larger muscles then a combination of cardio with some light weight lifting will work brilliantly.
The key here is getting the right balance of what to do, for how long and at what intensity.
I have trained many athletes competing in different sports, and each has required a different type of training. Each sport and each person has different requirements and different levels of fitness and adaptation. There is no set routine that will benefit everyone in the same way. Hence the need for bespoke training programmes.
When training athletes for their respective sports I will use some cardio, if they need to lose some weight and increase their overall fitness levels and some weight lifting if they need to build strength, speed, explosive power, and gain weight.
A greater ratio of fat is burned when doing moderate exercise, like walking for example, than doing more intense exercise. Intense exercise will burn more calories overall, but not necessarily fat calories.
So back to the original question, which is best? My answer is: they are equally as good as each other depending on what your goals are, and how you apply them.
For those that just want to lose weight, I will use various cardio equipment and exercises, and some weight lifting. The trick is doing the right amount, and intensity of each to reach the goals.
Doing cardio without weightlifting will burn calories and make you lose weight but muscle tone will be poor. Weightlifting without cardio will build muscle but not reduce fat stores as effectively and will result in less muscle definition. It’s all about the numbers: duration, intensity, frequency and rest.
So the answer, in short, is both have their place in most fitness and weight loss programmes. The trick is to do the right amount of each to yield the best results.