I wouldnt recomend any of them, i woul sugest u look into going on royal caribbean or princess, they got fantastic kids clubs from 8.30-early hours in the morning, and u can take ur kids out at any time, all the kids love the crew on these ships i think they are grea.
We cruised with OV2 this year and thought the cruise is OK with a kids club which operate from 9am-10pm. It's very laid back. Sorry, we haven't cruiseed with IC so I can't recommend which one is better. However, in my opinion, NCL is very good with family and it's also informal.
I cruised with Ocean Village last year and found the ship, kids facilities and childrens club fantastic so I can recommend them for a med cruise.
For under 9s I would suggest P&O as a great option- whilst the ships are more formal they do a lot for kids including a special kids tea at about 5 pm - my girls are 14 and 11 and have curised 2-3 times a year since they were 3 - they like P&O and we had some fantaistic holdiday when they were yoing , Ocean Village and Princess are also good with kids too . We thought NCL had less to offer . I would not suggest Island curises as we felt this was the least enjoyable of any of our cruising experiences and the kids agreed too.
I have cruised on both, and prefer Ocean Village, the children seemed to be having a great time, no matter age they were, Parents did not seem to see them at all.
We have travelled with children from 6 years up to teens with P & O and Princess and would thoroughly recommend them for children.
Just got back from cruise on Ocean Village in the Med with my 10 and 15 year old. Great activities for my 10 yr daughter - could do as much or as little as she wished. Activities from 10am-12midnight. By the 3rd day by 15 yr son had found similar teenagers. Both children, and my husband and I, did not want to leave the holiday after a week so that probably says it all! I noticed families with younger children having a good time as well so probably suits all ages.
Our kids are 9 & 3. we cruised with ocean village last year and it was great! haven't been with island cruises but have been with costa. they were also good but not many kids on board, not all of them were english.