I have no real experience here, but .net and .org usually are the best. The country domains aren't as good because I think search engines penalize them (like a us search for something will penalize the .co.uk results, and vice versa). I can't say that for sure, but I assume it's correct...
I have found that .org sites work very well in the right niche. I think it is because .org is often used in charity and not for profit sites so they have a presumed authority to the masses..
Something like BreastCancer.net is far inferior to BreastCancer.org but something like BuyCarTires.org is far inferior to BuyCarTires.net, so it all just depends on what the niche is..
Good point. An information site is better as a .org and a commercial is better as a .net...
Actually, this isn't necessarily true. if you wanted to lend an air of authority to a mostly commercial driven site, wouldn't a dot org be a viable option?.
Or let's say you want to market an entertainment site as if it has some educational value... for example AsianAnalSluts.edu..
I didn't know there was an educational market for asiananalsluts. Man you learn something everyday...
I did some quick research by checking out Spade's site NameBio.com - Domain name sales history, from namepros, and was able to do some basic ranking based on sales and avg. price. I don't think that this info has the final say in regards to which is the best secondary tld but it can help. Especially if you are just looking to flip the domain..
However, I'm more interested in long term traffic performance and sales conversions and resell value combined..
Total Domain Sales.
Avg Domain Sales price.
1 .Co.Uk 3,591.
2 .Net 3,079.
3 .Org 2,709.
4 .Us 1,375.
Interesting how the one with the least amount of sales has the highest avg sale price. That would probably come down as the volume went up but it shows there are some opportunities there...
It is totally dependent on niche and your intention for the site. Some .co.uk domains will be far superior to some .org's or .net's (HomeMortgage.co.uk better than BestDamnMortgage.org)However, as a general rule if only .com is taken I'd reg both the .org and .net and forget the rest. Some niches that are geo-targetted though would be better served by that geo's country code. For instance, for UK loan site I think you'd want the .co.uk rather than a .net or .org - but if you planned on expanding out of that niche, then you'd want the the .net or .org and you'd want to get subdomain like uk.bestmortgage.org. Really, it's a common sense issue as far as which domains you'll need or will be most useful to you. As far as sales though, .net's are the second highest selling (volume) after .com's.
That's why my advice would be that if you are looking for resale value or flipping the domain, to reg the .net. If you are looking to develop the domain you could have better luck with the other TLD's though...
Thanks. I've got more coming. I've made the same post at namepros and will compile all the info I gather and post it for everyone...