I've been to the Cyprus water park and Siam park in Tenerife. There is no contest, Siam park is just awesome. The wave pool is like a tsunami. Last year we stayed at the Olympic Lagoon hotel 5 minutes away from the park in Cyprus I think they call it Atlantis. It's certainly good compared to others I've been to but not in the same league as Siam Park.
I've never fancied it much but the dc would love it That sums up holidays with teenagers! I really wouldn't recommend the hotel we stayed in. Perhaps others will suggest somewhere. I would, however, recommend you stayed in PDLA or Los Cristianos because you are then 5 minutes by taxi from the water park. We factor in two trips to a water park on a holiday usually. They offer discounted tickets for a second day if you buy them on your first visit.
We stayed in Malibu Park when we went to Tenerife. Cheap and cheerful but clean and fine. We hired a car for the week which was great as we drove all over the island, up to the volcano, etc. I did most of the driving and it was fine.