Park Street C of E, without a shadow of a doubt. A small school based on Christian values but not pushy about them. Largely middle-class, concerned and very friendly parents who will introduce themselves at the gate and go out of their way to make you welcome. Fantastic pastoral support. I'm neither C/E nor middle class but was made very welcome, as were my DCs. Also a very enthusiastic PTA, the parents really care about the school, the kids, the community and education.
Great academic results, a mix of children, some locals, some from academic families on placement, which helps as although it's a very desirable school there are often mid-year places as people move on from the area. Some international parents (one of DD2s friends had an American Mum and Japanese dad, for example), but neither racism or OTT PC attitudes. Old-fashioned headmistress (reminded me of my own Miss - and very much a MISS - at my own Grammar school!). Staff know all the DC and families by name and personalities.
The only down-side is that the playground is so small that the DC use the local public space, Jesus Green, for breaks, thus there are passers by all the time but the DC are supervised of course and have strict boundaries to adhere to. Sadly there are a few undesirables there and needles have been found on the Green, which I wasn't happy with when my DC attended as my younger DD is an odd child with some problems and of the pick things up off the ground mentality and was only 5 when she went there (I didn't know about the needle problem when I enrolled them). However, I was content that my elder DD, 18 months her sister's senior, was able to adhere to the rules and safe... it was just DD2 who made me decide to move them from Park Street. Had it not been for her particular problems I would never have wanted them to leave!
Park St do a lot for and in the community and have good connections with local organisations and the Uni. Teaching staff are mostly older and with huge experience, patient, kind and knowledgable.
Two examples - I was diagnosed with cancer soon after my DDs started there. The school secretary, who even by then knew us well, reassured me... "You look after yourself dear, we will look after the girls". And they did! Parents I didn't even know came up to hug me and offer to have the girls for tea, help with the school run etc.
Also, when my DD (then 5) spoke to another girl the little one got upset and burst into tears. Instead of assuming my DD had done something wrong, the child's Mum immediately invited her to tea in order that the DC could get to know each other. My DD and hers became great friends.
I really, really, can't recommend it enough.
Other good ones were St Pauls (although the old head, Cindi Fiddy, has left, and I don't know what the new one is like, someone here has reservations) and Milton Road, largely very oversubscribed, good reputation and excellent academic results but comparitively big.
Hope this helps. There is one school in Cambridge I would suggest you avoid like the plague. The web will no doubt show you which, suffice to say that it's not in the centre but on the outskirts of the city boundary.
All the best!