I think I would go big. I would not buy a job. I would start 30bbl or larger, and recruit a known lead brewer from a known award winning brewery.
Basing this on my home brewing experience, lol. I have a pickup load of stuff from when I started to when I hit cruising speed. Financially, I should have started where I am, rather than waste 6 years and probably $500 on useless garage sale fodder. So, if I were of the mind to start a commercial brewery, I'd start at profit making level.