Domain Choice: MyKeywordPlusOtherWords.com or MyKeyword.net/.org?

Hi

I did pose this question on the Main board, but I think this is a more appropriate section, seeing as this is the SEO forum.

Apologies for the repeat.

So, this question comes from the fact that that a domain I want has been taken.

So, if mydesiredkeyword.com has been taken, which of the following would you go for:

- mydesiredkeyword.net

- mydesiredkeyword.org

- my-desired-keyword.com

- mydesiredkeywordplusotherwords.com

- otherwordsplusmydesiredkeyword.com


Additionally, what relative value of searches would warrant mydesiredkeyword.co.uk?

By that I mean, say, a term gets 3,000 global searches and 600 UK local (UK) searches (a factor of 5), and if I'm more likely to get a better ranking with a .co.uk domain, even though it is only for UK-based (and thus, fewer) searches, would you go after that, rather than trying to rank higher on the global searches?

In other words, what 'factor' (i.e, that which was 5 in the example above) would you deem to be good enough for me to opt for the UK listing, rather than fight for a global listing. (Big fish, small pond, etc).

Also, what do you think is a visitor's perception of a non-.com domain?

Do you think it is worth, say, going for a less Google-friendly (but still well-ranked) .com domain, instead of a more Google-friendly (but less visitor-friendly) .net domain?