Child isas or child trust funds. Depends on the exact requirements. Trust fund would be more controlled by you, isa I think would be parents responsibility.
I have a regular saver for my son via N&P, the interest rate is reasonable and the account is in my name.
I knew a few people who had family accounts in their name and the moment they turned 18 the spent the lot on cars, beer and going out, not something more sensible like a deposit for a house!