Jira Misc Workflow Extensions is a good choice. We have seen it in a lot of projects. It’s cheap but also limited compared the the others, especially PowerScripts.
Automation for Jira and Power Scripts are competitors. Automation has a nice UI. PowerScripts is more powerful. It is difficult to recommend one or the other. PowerScripts comes with a couple of pre-built scripts which is helpful for a couple of use cases. We do not generally recommend one or the other. This requires a workshop or at least an in-depth call to understand the customer requirements better.
You need to check with the customer if they want Big Picture Enterprise on top of the Standard version. Starting with Standard is fine, if you do not want to go with with our AgileHive. As we recommend to use AgileHive, you would need to consider BigPicture Enterprise.
Our recommendation could be, to get PowerScripts as it offers all relevant features.
Please let us know if you have any further questions.