The main question is not what you use team for, but why you need a team in the first place. As described earlier Teams is a digital office, with each channel being a room in that office.
Three main categories of teams
Since microsoft Teams is a flexible tool, there are more or less unlimited options regarding how to build your teams. These three are broad categories and covers most of the teams you need. By defining the purpose of each team, and preferably writing it in the description, you’ll help new members and admins understand why it exists.
Organisational
Not to be confused with org-wide teams, this is built as a structure for the organisation. One per department and management group.
Purpose
This is a work space for collaboartion, information and discussions.
Project
Every project has its own team, this is a place for cooperation within the individual projects. Often, but not always, you’ll find external guests here.
Purpose
Gather all information and communication regarding specific projects.
Topic
A knowledge center for different topics. This can be your Microsoft 365 Q&A or any team focus around your companies core products.
Purpose
Gather information in one place and make it easy to talk about the information you need.
Building teams with purpose
Since a team is a group of individuals working together towards a common purpose, a team in teams is where that purpose is communicated and documented. Every team need a leader, someone to empower to group to succeed. A leader need a group that follows and M365 have the tools to support it.
Set smaller goals, have a vision, engage, encurrage and motivate. These are the qualities of a teamplayers, my recommendation is to be a teamplayer.
Good luck!