A general question. Would launching a niche directory at the US market with a .net (rather than .com) TLD have a negative impact? Or does it not matter?
If specifically targetting a country I would say it does matter. A .us domain may get more clicks in google.us searches.
According to me the work behind your site is what matters and not the TLD. Make a quality directory and appreciation, traffic & submissions will follow.
I like .com extensions - but it is solely my personal preference. I may believe that .coms are received better but I have no hard facts to base that on. It is soley based on what is the first extension people think of when they think of www? That would be .com right. So if you don't have the .com address for your domain you may create brand awareness that sends people to other sites. If that makes any sense at all.
I agree with Swedal, most Americans think of .com for a domain name. I suspect many web users in my country don't even realize there are other extensions. Additionally, if the choice of a .net is being driven by the .com being already taken by someone else; I would definitely keep looking for a different name. You will have to work twice as hard to brand yourself. And why potentially give away the traffic you are working for to someone else?
The TLD doesn't matter, if your strictly targetting US only, then it would make sense to try and obtain a US, but really you could do it with many TLD's. Id be more concerned about where the server is situated then, because ive seen people say that a servers location can make a difference in your ranking when say your targetting the UK. As swedal points out though, what people are used to typing in, you mention websites even to ordinary non geeky folk and they think .com Given the choice of settling for a .net or .org because someone already has the .com or choosing a different . com id go for choosing a different .com Id buy .net. org .mobi etc if i already own .com and want to secure a few of the other main extensions.
not sure if .us would be above .com in stating the site is us based as .com historically means this for other regional tlds though I think it makes a difference and however slight its worth to use the related tld in the long term when you submit to regional dirs some will have restrictions on acceptance based on tld so you have some advantage then too as mentioned country of hosting I also think has some bearing
Shouldn't matter a bit with regards to standard surfers as they will go for whatever is higher in the SERPS regardless of .com