We moved to splunk now and mostly happy with it, mix of windows/linux/etc logs.

But with AI, I can see opensource alternatives getting better.

I've never been in the sales room. I've heard from multiple corps that Splunk is quite expensive. I've been to one place that ran its own Elastic stack, which was a bit of cost in its own right because they had to run all the infrastructure and storage themselves, and had two FTEs whose main job was keeping the thing running. I don't know what Splunk offers from a UI/features perspective that Kibana couldn't do.