I have stayed at the Delphin Palace and Limak Lara but toured the other 2 hotels.
The Delphin and Royal wings have the fun fairs so may be more fun for your 6 year old .All will have childrens clubs so your 6 year old will be well catered for.
The Delphin has several Al a cartes and they are inclusive whereas the other hotels have charges for some. Drinks choice best at the Delphin with bottled beers like becks included.lovely pier there. The Delphin Diva is also one you might like and usually slightly cheaper than the Palace and it has a fun fair. It was fully renovated a couple of years ago.Same concept as the Palace.
Royal Wings is very popular but fun fair and water slides at the front of the hotel so you would have to go round there to use them.