Which is an effective and easy to use communication tool for businesses?

It is on my view the interop. Communication should be platform independent but unfortunately for business, each one is promoting a different standard.
Microsoft Teams jumped ahead thanks to the O365 integration (at the time). 

Having used both, I like Teams better. It’s more intuitive.

I've found that all of these meet the effective communication tool checkbox (from different perspectives).  MS Teams is great where Microsoft is entrenched in your organization and you want to leverage their tools for collaboration within the scope of MS Teams.  Webex has delivered excellent audio and video quality for meetings and has been great for our public facing events and robust easy to interact with attendee experiences.  Zoom has definitely been the leader on the accessibility and ease of use fronts on the Meetings front.

In my personal experience, I've had success getting my ~60-year-old mother on Zoom. If she can do it, everyone can.

Microsoft teams allows not only better collaboration but ability to have everything under one roof including chats, calls, files, calendars and mails