The common trend we've seen is that most of these other projects are okay for a true "just send messages to an AI and get responses" use case, but for most things beyond that they fall short / there a lot of paper cuts.
For an individual, this might show up when they try more complex tasks that require multiple tool calls in sequence or when they have a research task to accomplish. For an org, this might show up when trying to manage access to assistants / tools / connected sources.
Our goal is to make sure Onyx is the most advanced and mature option out there. I think we've accomplished that, so if there's anything missing I'd love to hear about it.