In Boston, is Concord Pike or M Pike less congested?

I commute westwards to Framingham and am trying to decide whether to live in Somerville (near Davis Sq) or Cambridge (near Central Sq). I have noticed that the ramp going onto I-90 are quite congested after work (though I am not sure what the situation is like in the mornings). Is the traffic on the ramps leading into/out of Concord Pike Rt-2 any better?