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).