If the name you want is already taken would you opt for one of these or change your name all together?
I would go with .org. I just bought a .tips to test out on a new niche site I'm building up till now I had about 150 all where .com, .net and .org with one .info. But if the .TLD's work it will be cool you can get almost anything now, I just don't know if they can rank. Time will tell, I'm starting to build it in the next few weeks then promote it, lets see if it works. But in your case I vote .org. Good luck.
If it's something that belongs on a .Com, I probably wouldn't go with any of those. Especially, the .US and .Org. I'd probably go w/ a .Co, maybe a .Info, or find a new gtld that would make sense. However, it really all depends on the particular domain.
.NET every time .ORG is mainly used for non-profit and charity organizations .US is hardly recognized by companies, its more of a domainers extension
It depends. If your business is complete unique or if it is an eCommerce then have .com to be the main site and link other TLDs to the main site, so that no one can have your business name later.
As a general rule, I would change my name in order to register an available .com rather than settle for a .org, .us, or .me, but there are exceptions to every rule, and in those cases, the domain extensions you listed could be a good alternative. For example, for open source projects, non-profit organizations or anything with a social, political or religious current to it, .org would be a good fit. As for .us, I can't think of a good reason off the top of my head as to why I would register that domain for a project as an alternative to .com, unless the project is political, particular to neighborhood, city or state, or it was a single, dictionary word. .me could work for a personal website or blog, a personal service such as email, but I don't believe it works well for a general website. In fact, wouldn't use any of those domains for general, commercial use. Instead, I would change the name or riff on the name, adding some secondary word or phrase before or after, until I found something available.