dont depend too much on tripadvisor !

How many children and what are their ages ?
what is your approxiamate budget per night?
Would a villa possibly suit you?

This will help people here to advise you accurately.

Ko samui is a well developed family orientated island. There are many resorts from luxury to budget . I personally like Baan taling ngam at the luxury end and have many recomendations for all budgets.