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!