Every other theory requires involving many more unsupported hypotheses.
This would be obvious to the majority of the HN population in most cases, but the disinformation in this case is apparently quite effective.
How do we know that the virus (or a precursor) wasn't already circulating in China, and was simply detected in Wuhan because of the fact that there are experts in coronaviruses who reside there?
(Also I'm not entirely sure your statement about the gain of function research is correct. A Google search doesn't seem to provide any evidence one way or another.)
Even if true, that would not explain the elaborate story, regarding the wet market there and species-jumping.
Also, seems unlikely, as there'd have to be reason to suspect a new virus was circulating at scale that required investigation by these scientists, which could have happened anywhere in the country. I mean, it's hard to understand what mechanism you're proposing for scientists residing in the city leading to the discovery of the virus circulating among the population there. It's not like the scientists simply roam the streets with some superhuman ability to detect new viruses in people.