Broadly, I think other open source solutions are lacking in (1) integration of external knowledge into the chat (2) simple UX (3) complex "agent" flows.

Both internal RAG and web search are hard to do well, and since we've started as an enterprise search project we've spent a lot of time making it good.

Most (all?) of these projects have UXs that are quite complicated (e.g. exposing front-and-center every model param like Top P without any explanation, no clear distinction between admin/regular user features, etc.). For broader deployments this can overwhelm people who are new to AI tools.

Finally trying to do anything beyond a simple back and forth with a single tool calls isn't great with a lot of these projects. So something like "find me all the open source chat options, understand their strengths/weaknesses, and compile that into a spreadsheet" will work well with Onyx, but not so well with other options (again partially due to our enterprise search roots).