Upgrade to windows 10

Hello, everyone,
We currently have windows 7 pro deployed across the organization (approx. 140 machines), we also use Office 365 E3, for email, On the drive, teams, etc.
I’m looking to upgrade to Windows 10, but I can’t seem to figure out what would be the best option.
I was investigating the options for Windows 10. also I think that there are only two ways.
1- the traditional way, using Volume licensing, purchasing a Windows 10 key.
2- Purchasing Microsoft 365 licenses which are essentially the Office 365 E3 plus Windows 10 plus some mobility administration. The problem with that approach is I’m not sure if it’s something that would apply to our environment, considering we have on-prem Active Directory and we use Group Policies heavily. I read that it may not apply, but I can’t figure out why, and I can’t get a straight answer from MS.
The other thing is, with the understanding that Windows 10 is the last version of Windows, does the Volume licensing model make sense?
So, I’m wondering if there is anyone who is facing the same issue that please recommend me in the right way.
Thanks a lot
Great cheers