I am unaware of a service which really aggregates multiple view points in a fair way because such a thing is impossible.
I can link you to a few longer form journalism papers/magazines, but any conservative would decry them as biased.
We could link to some traditionally conservative outlets, but they'd be decried as neo-conservative, out of date and biased.
As offensive as it might be to you, in society and news, opinion is all there is.
"But facts MATTER" you might retort, but no, they don't. Only opinions about facts matter.
Because what power does a fact have if it's not accepted as true? None. What power does a falsehood have if it's accepted as true? All of it.
There is no fair and rational way to separate opinion and fact.
After a fifteen years of using news aggregators, RSS aggregators, aggreagtors like memeorandum.com and polurls.com, and social aggregators like digg, then reddit, and social media services, I have not found what you want.
I have thought about making it, and I have ideas on how liberals and conservatives can use a single website to organize the news into strands and voice their opinions on the validity of that organization WITHOUT the normal animosity and viciousness that is normal, but I've never sat down to really create it.