How many kids do you prefer to have per couple?

It entirely depends on how long I wait for my sims to have kids. If they have kids early in young adulthood they end up with what feels like a battalion (usually resulting in me giving up because I can't keep them all happy, and moving on to another family). If I wait until they're at least coming to the end of young adulthood I limit it to three kids, max. That way I can pick a favourite to continue on with, yet still be able to build skills for all the children before they age up.