Long time BlackBerry lover here so I maybe biased. My Z30 is now a few weeks old and I still find it to be a incredible phone. The build quality is second to none. I played with the galaxy Note and it felt cheap in my hands. Some people think that the Z30 is heavy but I like that it means I have something that isn't cheap Chinese plastic. I don't recommend doing this but my Z30 is in a defender box and I had it on my bath tub wall. My dog pushed it into the water. I got it out quickly but water still got into the speakers and mic. The next day my camera lens had water on it. The phone never skipped a beat though and in a few days the water cleared up and the camera is clear as a bell. I don't have any problems with anything phone works like new.
My friend has a 5s in a life proof case and she had the plug out for the head phones dropped her phone in her coffee (she was driving and texting not smart lol) was in there for a second. The 5s didn't make it screen flickered and then went out. That's pretty sad. So the moral of the story is I find the Z30 to have a great build quality and it is an awesome phone!!
It's always interesting with phones and water. I remember reading an article not too long ago about a Nokia Lumia that was in a lake for months. When the owner found it again, it worked perfectly. I think it's all just the luck of the draw