It depends on what do you need a SaaS product for. There are different tools for different purposes so it would be difficult to name one, all-around best product. We use or have used many tools at our company and here are a few of top off my head:
-Trello for task management
-Slack for internal communication
-Intercom for communication with our customers and potential customers
-Hotjar and Heap for web analytics
-Brand24 for social media monitoring
