I'm rebuilding part of my lab, and I need to deploy a new file server for profile management tools. I don't want to build a new Windows file server, so what are people using for a virtualized NAS or file server these days? Active Directory integration and SMB shares are the main features I need, and open source is strongly preferred due to budget.

honestly i'm just using the same NAS devices i use for vm storage, etc.. a synology and a terramaster unit

You could do a virtual truenas

I switched to TrueNAS SMB/CIFS earlier this year. There can be some headaches if you end up on a version of TrueNas with bugs , but once it’s working , way less maintenance than a standard windows file server