Which TLD should you seek as the 2nd best option if a .com isn't available? I'd personally rank .org as next in line - just experience, not cold hard data or any new excerpts, etc.
I've done ok with .infos (even without SEO efforts - just driving traffic through social media and the SEs picked up on it then starting sending organic traffic). Anyway, but when I can't get a .com, I then aim for a .org or a .co.uk, or a .net, depending on the nature of the project/customer demographics needed.