Do you guys know a best PHP Encoder software?
What do you mean by the best? Most are paid solutions (often require server software installation). It depends on how big your project is, or if you want it to handle variables that are included in one file and used in another. And in the end of the day no amount of obfuscation can fully protect your code if that is your concern (theft).
Anyways, Zend Guard is a good solution.
What is the advantage of Zend Guard software over https://www.ioncube.com/php_encoder.php
Well, it is more robust in my opinion, but this is subjective of course. That is why there is no such thing as the “best”. On the other hand, yes PHP Encoder is way more cheaper and is now also backwards compatible. So I guess for the price it is perfectly fine and again, it depends on your project.