What are the trade-offs between building a customer-facing experience with OmniStudio versus custom Lightning web components?

Both produce LWC at runtime, so the question is really about who maintains the thing over the next three years and how much of the requirement is standard.

1. In favour of OmniStudio: guided flows, validation, conditional visibility, server orchestration and versioning come for free. A business analyst or admin can adjust a question or reorder Steps without a deployment pipeline. Industry implementations get to a working prototype far faster.
2. In favour of custom LWC: full control over markup, styling, accessibility details and interaction design. Unit testing with Jest is straightforward. No dependency on OmniStudio's runtime or upgrade cadence.
3. The usual answer is both: OmniStudio for the flow skeleton, with custom LWC embedded where a specific interaction cannot be expressed declaratively. OmniScripts support custom LWC elements precisely so teams do not have to choose all or nothing.
4. The cost to flag honestly is skills: an OmniStudio codebase needs people who know OmniStudio. If the team has no exposure to it and the requirement is a single simple screen, a plain LWC is often the cheaper long-term choice.