Neither is "better". They both contain testosterone esters which are converted into testosterone by esterase enzymes in the bloodstream. So the only difference between them is how fast they are absorbed into the blood.
Enanthate has a half-life of 10.5 days. Sust is a blend of esters...some with a short half-life and some with a very long half-life. If they are both the same price per mg of test, then I would choose enanthate. A shot every 5 days would be plenty with that half life and it would leave your system quicker then the long chain ester in the sust at the end of the cycle when it was time to start PCT.
It all comes down to preference. I've used both with excellent results, but I like Sust better for some reason. Enanth is extremely popular as well. Test is test though