Google Analytics, WordPress and Sumo serve different purpose. WordPress is a Content Management System use to create websites. It is the easiest and most powerful content management system used to create websites and blogs.
Sumo is the platform where you can build the subscriber list, share content and monitor your content efforts. It also provides the heatmap functionality which allows you to find whats hot and what not on your website. The good thing is you can intigrate Sumo with Google Analytics.
As the name suggests, Google Analytics is a free website analytics service offered by Google that gives you insights into how users find and use your website. With Google Analytics, you can track ROI for your online marketing. The service is available to anyone with a Google account.
There are web analytics companies (https://www.radon-media.com/services/digital-intelligence/) who helps with Google Analytics set up and monitoring.