VLANS- On the Server, or On the Switch(es)

So, our little Intranet of appr. 45 drops is going big time. We are going to implement VLANS for isolation and segragation. Simple question- I see that you can setup VLANS from your Router or from your Managed Switches. I had assumed that this would be done from the switches using port mapping as this is an existing installation, and all the home-runs are in place. One of the other IT techs has suggested (or seems to be suggesting) that we do it in the Router (Sonicwall TZ215 or equivalent). Which is better or more proper? We have 1 Router (soon to be upgraded to the Sonicwall or equiv.) and two 24 port managed switches. I understand the basics of VLANS etc. but have never implemented them. So, advice on this, please? TIA