I've stayed one week in the Cinque Terre, it is truly beautiful indeed. All villages are utterly charming and I don't think it really matters which one you stay in, they are very close to one another. I myself stayed in Levanto, a nearby town, cause I wanted to be amongst Italians rather than mostly with other tourists.
As beautiful as the villages all are, I preferred the walking trails up in the hills, cause the villages are very crowded during high season, taking away a bit of the charm.
I wrote an article about slow travelling in the area, if you are interested: http://www.myfeetaremeanttoroam.com/travel-guide-cinque-terre/
Enjoy your trip!