This app I use for all my clients, it has two settings.
Basic and Advanced.
With the advanced feature I am able to setup all the requirements I need using simple rules and advanced regular expressions.
Ofcourse each result may require a different kind of setup, but I have not found any limitations using the app.
I do also manually improve data using a supplement feed in Google Merchant Center, however the app also allows you to manually edit every value seperately.