WWW or not WWW, what to choose as primary site name? [closed]

From technical perspective the only issue is traffic and incoming links (one of them should redirect to another).

Now I need to choose which one should be primary. Some sites have www (google, microsoft, ruby-lang) and some without www (stackoverflow, github). Seems to me the newer do not use WWW.

What to choose?

Please with some explanations.

UPDATE: This is programming related question. Actually site is for programmers, so I expect to see what techy people think.

UPDATE: Site without WWW is clear winner. Thank you guys!

Solution 1:

It doesn't matter which you choose but you should pick one and be consistent. It is more a matter of style but it is important to note that search engines consider these two URLs to be different sites:

http://www.example.com
http://example.com

So whichever you choose for aesthetic reasons should be consistently used for SEO reasons.

Edit: My personal opinion is to forgo the www as it feels archaic to me. I also like shorter URLs. If it were up to me I would redirect all traffic from www.example.com to example.com.

Solution 2:

Don't use WWW. It's an unnecessary tongue-twister, and a pain in the arse for graphic designers.

Solution 3:

There are some issues you should consider. See for example Use Cookie-free Domains for Components for a cookie validity issue.

But regardless of how you decide: Use just one of that domains as your canonical domain name and use a 301 redirect to correct the invalid. For an Apache webserver, you can use mod_rewrite to do that.