Sustanon is a mix of four testosterone esters. Testosterone Enathate or Cypionate are sinle-ester testosterones.

For the purpose of this explanation, think of an ester as a 'time-release mechanism' for a steroid.

With a single ester test. (En or Cyp), you have a very simple time release mechanism. With Sustanon, imagine you have four different size buckets with different size holes, each releasing their testosterone at a different pace, and you have to refill all four at the same time--so you can see how it's hard to keep blood levels stable.

Injecting Sustanon one time a week would cause the levels of testosterone in your blood to swing quite a bit. If you do it 2X a week, it's less of a problem; 3X weekly and you are looking at pretty stable levels--but then you are doing 750mg of test a week--and that's a LOT! With Test. En/Cyp, you will get pretty stabel levels with only one injection a week, so you can keep stable levels with a fairly low dosage.

Sustanon is not bad by any means. They all do the same thing in different ways. I am using it right now; just in most cases, Test. En/Cyp does the job and is easier to manage.