"Best" will be chosen by the creators of software for specific application uses. Medical software will use the "best" medical LLM under the hood. Programming software (Copilot et. all) will use the "best" programming LLM. General purpose language models will probably still be used by the public when doing internet searches. Or, an idea that just popped into my head, use a classifier to determine which model can most accurately answer the user's query, and send the query off to that model for a response.