Microsoft has provided some great resources for you to analyse your environment and make an informed decision.

Check out the Network planning and performance tuning for Office 365 article from Microsoft for further information, definitely a recommended read!

Exchange Client Network Bandwidth Calculator

The Exchange Client Network Bandwidth Calculator has been designed to help anyone planning an Exchange Server deployment to predict the network bandwidth requirements for a specific set of clients.

Lync 2010 and 2013 Bandwidth Calculator

A Microsoft Excel spreadsheet that calculates WAN bandwidth requirements for a Skype for Business Server and Lync Server deployment based on administrator-specified user profiles and network information, and a Word document user guide that accompanies the spreadsheet.

OneDrive for Business Client Network Bandwidth Calculator

The best method for determining bandwidth requirements when deploying OneDrive for Business is to measure the bandwidth used during a small roll out.
If this is not possible, this calculator can be used to provide a loose estimate.