Which is better and which is more fun? Whats better value for money?

Aquopolis is considered to be slightly better value than Costa Caribe (now called Port Aventura Aquatic Park).
Out of the 3 and if forced then I would pick Aquopolis but it is hard to compare as it is a different experience.

My vote goes to the Portaventura theme park every time. Lots of fun for everyone. I went to the Portaventura waterpark last year and only stayed half a day as my son got bored where as the theme park we had 3 full day and enjoyed every minute of it.
It is down to personal preference though as we are not big waterpark fans.