What's a good SIEM for a small office?

I am looking for a SIEM for a small environment, 100 users, 12 servers.

I have a limited budget, so I've looking for open-source setup.

Currently looking at things like Wazuh, Security Onion, OSSIM, etc.
What are you thoughts on these, or other SIEMs for a small company?
I think ELK and Splunk are too big/expensive for me.

budget cybersecurity elk environment etc good office onion security servers siem things thoughts wazuh