It really depends on what you mean by 'best return'. It also depends on their current age(s) and when you want to give them control over the money. I also assume you mean children, not goats.
Safest - probably a building society or bank account for each of them. Make sure that the income tax relief form is signed though. Also, don't necessarily be fobbed off with a children's account as not all of these are as generous as they probably should be.
Consider Premium Bonds - no capital increase and not necessarily any winnings... but they just might win a million.
Depending on your own tax and marital status, look at trust fund options - keeps the money away from the children (and you!) until they reach a specific age - and could be invested in the FTSE or other stocks/bonds/etc.
If you have a financila adviser, talk to her/him.
FYI, my son has a bulding society account of which I am trustee - he can't have access until at least the age of 16; also, his grandparents give him premium bonds and a god-mother gives him NS&I Baby/Children's Bonds.
Hope this helps.