To me, does it really matter if a waterpark is themed well? As pointed out before SFStL HH is while Noah's Ark really isn't. This is how I can compare. It might sound stupid, but this is my way.
What's the best ride that each park offers. For Noah's Ark, it's Black Thunder (middle slides) no question. How many more (favorites) are there? I would probably say 5 or 6 more. Minature golf is good. Let's remember that one slide complex can have three or even four slides.
My point is that if HH doesn't possess any great slides or have slides that become my favorite slides, how can I rank that higher than Noah's Ark? We are discussing which one is going to be better when one isn't even open yet.
Theming doesn't mean much to me. If a theme concept is popular, it could get people into the park (Marvel area at IOA), but the rides mean more to me than anything. So, for right now Noah's Ark.
A complex with a lot of slides on it (to me) means you don't have enough room in the waterpark. I would rather have more complexes with less slides on each.