I tend to have internet radio, sourced from a couple of main websites devoted to old British radio comedy, playing in my headphones for much of the time. Should I count them? If so, ROK Radio should probably be at the top of my list
http://rokradio.com/
with Abacus FM also included:
http://www.abacus.fm/
Otherwise the site I spend most time on has to be The Answerbank, with Youtube a close second. (I'm into world music, so I'm always looking for something new).
I visit the BBC News website, together with those of the East Anglian Daily Times and the Sheffield Star, several times per day but (since their content only changes slowly) the total time I spend viewing them won't be as great as that for the sites I've mentioned previously.
(I'm sorry that I've not provided just three sites, as you requested, but it's hard to know whether, say, having internet radio playing in the background while I'm on AB, counts as 'spending time' on the radio site).