Small house or townhouse in the city or within a couple of minutes walk of the city, if I didn't have any kids then apartment in the city would be fine too.
Where I live isn't really a city but a smallish town of 75,000 but it still has an urban core with plenty of retail, commercial, leisure facilities, restaurants, bars, rail station etc and traffic congestion that means a big convenience advantage if you live near enough to walk in.
Other things being equal, the larger space of a detached suburban house would be great but other things aren't equal and the extra inconvenience of being further from everything outweighs the advantage of extra space for me.
As long as we have enough space that's fine by me and the 110sqm + small backyard we have at the moment is enough for two adults and two young children to live comfortably. When the children are bigger we will probably want a larger home with more outdoor space but I'd rather look for a bigger townhouse than go further out into the suburbs, I'd only move further out if I couldn't afford that bigger townhouse.