I base it more on the kids I have in care at the time I have a space to fill so it stays balanced. I find when it is all boys that they tend to be more active and need more reminders of how to behave in the house. When it is all girls it can sometimes be harder to encourage the active play and there tends to be more drama, tears and whining. Ok so sounds sexist I know but just something I have observed.

If taking on a boy who has older male siblings expect them to be rougher and more active sooner. Also in the interview ask questions about what future activities they see their child doing as that will give you an idea of how they intend to raise the child if you are concerned about activity level in the daycare.

Generally speaking I don't have a preference but what I really like is to have a boy and girl at each level of development as they compliment/balance/encourage each other and it helps them to develop more rounded play interests.