Neither an ESTA nor a Visa guarantees entry to a country. This is valid for each country in the world -the final decision to allow you entry or not to the country is made by the immigration officials at the border at the time of entry.
All the more particularly to your case, the chances of being dismissed with an ESTA Immigration USA are fundamentally the same as being dismissed with a Visa – and in both cases are to a great degree low.
When all is said in done the main reason that would bring about your entrance to be denied is if the movement official trusted that you were endeavoring to enter the nation wrongfully as well as against the terms of your visa/VWP.if you have an ESTA USA or a B1/B2 visa, but the immigration officials believed that you were coming to the US to and to stay more than the time allowed by your Visa/VWP..
If you do nothing wrong, are entering within the terms of the Visa Waiver Program, and have truthfully completed your Electronic System for Travel Authorization application, then there is absolutely nothing to be worried about.