Move to a new version

To the question: When companies decide to move to a new version?

Some sellers’ reply: when a new version is released, companies love, need, appreciate new features and capabilities of new versions. In other case, they can be loose competitive advantage.

Some buyers’ reply: when the current version we have is not supported by the vendor, it supposes a risk for us. Now is we have to check to which is the most convenient version for us.

In which os the event’s happens the major number of versions move?