We went to the Tenerife one (before DD came along) and from what I remember the kids club was excellent but you had to queue to get a place, as it was always full. This was about three years ago, so may have changed. Maybe check on trip advisor as you normally get feedback there on childrens' clubs?
We went to Sensatori Crete and really enjoyed it with our then 5 year old. The children's pool is fantastic and ds spent the whole day with us by the pools. He did go to the kids club once which he enjoyed. Personally I would avoid the summer school holidays as it was very busy and I sometimes felt the staff were a bit stretched. Any other questions, please ask.