To me size doesn't equate to quality and I don't necessarily think big is better or even that smaller is better. There's good and bad aspects in networks of all sizes. It depends what the user is looking for. Smaller networks are, at times, better staffed (ie: more opers per a given number of users) despite the fact that it doesn't always appear to be this way. Larger networks at times have fairly busy rooms though they arn't always rooms for chatting, they'll be file sharing rooms instead. One notable exception being Dalnet who has a filesharing policy similar to the network I use which means that filesharing rooms are specifically forbidden. Some of the other big networks seem to thrive on it.
If your network has a family atmosphere, good quality services, well-mannered opers and a half decent website that is able to capture the market (or at least some of it), then it will get some users.