It depends on the city I guess. Living in a city like London, Amsterdam or Paris (for example) is worlds away from living in cities like Cambridge, Bruges or Luxembourg.
Ages of children is a factor too. Teenagers might love a city, whereas most smaller children would love the country. Some teens would love the country too, but there would be occasions where they'd want to go to the cinema, bowling and in their older years, the pub, the nightclub etc (and of course the adults enjoy things like this too on occasion).
As someone else says, it is a very personal choice.
For me, I think either a small city or large-ish town nearby is a good thing (a decent rail link an advantage), but not necessarily having to live right in the middle of that city or town so long as you are prepared to fork out cash for taxis or spend a lot of your time being a chauffeur for family and friends.
The trouble is, Singapore is a very easy city in which to live and I don't think a lot of us really appreciate it until the time to move back comes along and for us that time is coming along very soon. There's a lot I won't miss about Singapore but a lot that I will

Good luck, whatever you decide. We've been here 12 years - it's going to be a bit of a weird feeling to know that when we go we'll be gone for good.