Try the Paffian Sun in Pathos Cyprus - Thomas Cook - I think. All inclusive up to 16. But remember that also means lots of younger teens. We went 2 years ago when our girls were 11 & 15 & had a great time.
It really does depend on what you look for in a holiday because there are so many different places!But my suggestion is San Miguel Beach Club in Ibiza!Amazing place for all the family and is All Inclusive upto 16 years!Thats why we are returing for the 4th time as it is one of the only places that takes my 16 year old daughter!Hope this helps!
Any of the Iberostar hotles - they are very family friendly and a good standard of accommodation & food - a bit pricer than many , but well worth the extra.