Saying that relativity is "the best theory" is not very different from saying that it won. Stuart says that it won because it was simpler than Lorentz contractions. It was not widely believed to be the best theory in 1915. What happened between then and now? Was it obviously better and the old guard just had to die? Or did something else that happened, like the Nobel or GR change people's minds?

I'm not sure that Lorentz's transformations were more ad hoc than Einstein's, though Minkowski's were a definite improvement. If Einstein's principle lead to Minkowski's work, that's good, and meets Vladimir's usability criterion; and probably counts as simplicity.